Removing '05 GT Camshaft Position Sensor P0340

How did you disconnect the alternator? Power and signal wires? Did you reset the ecu before starting with the alternator unplugged?

So you've gone through the FSM troubleshooting procedure testing resistance, power and grounds of the sensor, wiring harness and ecu without issue and you've removed the alternator from the system to eliminate noise?

To me, the next step is to check mechanical. Verify that your timing belt is correct. Your camshaft or cam pulley may be damaged.

Hi Rhino,

To answer your questions specifically....

How did you disconnect the alternator? Power and signal wires?

- YES

Did you reset the ecu before starting with the alternator unplugged?

- YES, I disconnected the negative terminal on the battery before disconnecting both cables from the alternator.

So you've gone through the FSM troubleshooting procedure testing resistance, power and grounds of the sensor, wiring harness and ecu without issue and you've removed the alternator from the system to eliminate noise?

- Not exactly. The sensor has already been replaced 3 times and the portion of the wiring harness that connects to that sensor has been replaced (sensor bundle to firewall connector). In the summer, there is no code and no problem at all. In winter, once the car warms up completely, I can clear the code and it will also run perfectly with no code. So I don't see how it could be a sensor / harness issue.

To me, the next step is to check mechanical. Verify that your timing belt is correct. Your camshaft or cam pulley may be damaged.

- Again, if the issue happened under all conditions, I would agree. But the fact that it only occurs under very specific conditions and with very predictable symptoms make me think it's not mechanical.

Tonight I will look again at the service records from the previous owner and see what I can see. I saw some other posts about injectors and plugs / wires possibly causing similar issues. If those have never been replaced, maybe it's time to try that next.

Thanks for all the replies.

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Well, if anyone is still paying attention to this, I found an interesting WRX TSB that describes my issue almost exactly. Subaru actually provided dealerships with a shim kit for this issue on the newer WRX.

So I think when I get a chance I'll pull the sensor out, take some measurements and maybe make a shim that will fit under it. At this point, I'll try just about anything.

Thanks for reading.

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SB-10052498-5734.pdf

Just a quick update...

I removed the sensor again and made some temporary shims just to see if they had any effect (based on the TSB I mentioned). I used adhesive, aluminum duct tape that I cut into the shape of the sensor and it worked out pretty well. Doing it this way allowed me to start with a thinner "shim" and then add thickness to it to see if it changed.

Unfortunately, it didn't seem to help. And now the warmer weather has returned, so the problem is gone until next fall.

Not giving up yet, though! Over the summer (once all this Covid nonsense is done with and I can get parts more easily) I'll replace all the plugs and coil packs and see if that helps. I also might do some exhaust work and get an e-tune for it. But that's just for funzies.

I'll update again in late September when I expect this to start happening again.

Peace.

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This might sound somewhat silly, but I came across a similar set of symptoms and it manifested more in the cold too. It turned out to be a poor connection on the coolant temp sensor. Basically right behind the alternator on an EJ255. Once I replaced that connector it solved everything. In your situation i wonder if your coolant temp sensor is failing.

Did you ever try messing with this coolant connector as suggested?

Did you ever try messing with this coolant connector as suggested?

Not yet. As I mentioned above, the last thing I tried was the shims but that was because I had a couple of cooler days in April where the problem still arose. I'll definitely look at it in the fall when I'm back into my cold weather troubleshooting.

Thanks for the interest. It's so nice to be part of such a helpful community.

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Any luck with this over the winter?

Well, yes and no. I'll explain where I'm at so far in much more exhaustive detail than anybody is likely interested in.

But first, a quick shout out to Max Capacity for sharing the service manuals (I believe it was in the 3rd or 4th post in this thread). Without that manual, I would have been continuing to shoot in the dark out of ignorance. So here goes....

2 years ago now, I brought the car into the Subaru dealer in Detroit (closest one to me, despite living in Canada). They swapped out the cam position sensor for the 3rd time (against my advice) and it didn't fix the problem. So then they swapped out the wiring harness and it STILL didn't fix it. So I got the car back and said thanks, but I can't afford to have you guys keep guessing.

So, for the past 2 years I've been thinking it WASN'T wiring related since the harness was replaced, so that's why I was trying shims, I swapped out the TGV gaskets, I tie wrapped all the vaccum lines. I tried everything I could think of.

Then, I reached out to Dave at CryoTune because I was thinking about tweaking the car a bit and wanted to know if this P0340 problem would inhibit that. He said it wouldn't be a show stopper, but in a perfect world having it fixed first would be preferred. Then he said something in one of his emails that stuck with me. He said "that code is usually pretty accurate". Hmmm.....so I started digging again into what the code is actually telling me. It's definitely a wiring issue. It means that the ECU sees something in the cam position sensor CIRCUIT that it doesn't like. So, I went back to the manual that Max Cap posted and started reading (which I really should have done in the first place, and which the dealership in Detroit should have done as well).

Anyway, on pages 2048-2049 (yeah, it's a 6000+ page manual) there's a step by step troubleshooting procedure for that specific code. So I got out my volt meter and started testing. I got as far as step 5 and all indications point to a short circuit to ground. But how could this be? They replaced the harness, right? Yes...but which one?

So, I kept looking through the manual and found the engine electrical diagram. it seems that the ground wire from the cam circuit shares a connection with the ground wire for the engine temperature sensor! And this ONLY happens in cold weather! Hmm....

It's a bit hard to follow, but if you look pictures 3 and 4 and find the circled #6, that shows the connection between the different pages. Then you'll see the ground common between the two sensors (cam and temp). So I think that's it.

So, back to your original question, this is the "yes" part of my answer. I believe I've found the problem.

The "no" part is that because I moved last September and no longer have a garage in which to work on this beast, I haven't gotten back into fixing it. I have family nearby where I will be doing the work, but Covid pretty much ruined everything. I have $2000 worth of upgrade parts all paid for, waiting for me in Detroit, but because the border is closed to non-essential travel I haven't been able to get over there to pick them up. So, once I have all my stuff in hand ready to go, I'll dig in, fix this issue (I hope), upgrade a bunch of parts (turbo, exhaust, etc), get Dave to e-tune the heck out of it, and I'll be off to the races.

So....there's your (very long winded) and evasive yes/no answer. Hope all the detail serves to help somebody! And of course, once I get to fixing it, I'll post the results. I hope to finally put it to bed within a month or so. I have a work trip to the US coming up soon and it will be my excuse to cross the border and collect my new toys. As always, thanks for reading. I love this community and all the help and support I've received.

Peace!

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Right on, I hope you get it sorted you can install those new toys and boost with confidence!

Back in the day with my 93 turbo wagon and having crank sensor intermittent issues I got a plug from the junkyard, completely bypassed the wire harness, and ran a whole new signal and ground wires to the ecu to get the thing going. Later I found the heat-cracked and worn 250k mile wires when I pulled the motor for a clutch or something. Good luck!

So, it's been a while since I posted anything about the camshaft code I've been getting (P0340 - Camshaft Position Sensor Circuit A) so I figured it's worth a quick update.

It's summer here in southwestern Ontario, but we actually had a cool morning a week or so ago. Not crazy cold....about 10 deg C. Just cold enough to reassure me that my cold weather problem is in fact STILL an issue. I thought I was on to something when I saw the sensor ground was commong to the ECT sensor ground. I replaced the engine coolant temp sensor in the event that it was at least part of the problem. No dice.

I've been modding the car for a couple of months now (very slow process with Covid / work travel / quarantine / etc.) but I've finally got all the parts on, got all the air leaks fixed and I'm now getting it e-tuned. (Shout out to Phil at Dynotech in New Zealand. Doing an awesome job.)

During my mods, I found a broken ground strap under the engine on the passenger side. From the looks of it, it's been missing for a while. The engine bolt was nowhere to be found and all that was left of the ground strap was the metal crimp end bolted to the chassis. So I replaced both front engine ground straps.

Now for a little background on my diagnostics - see my above post with the manual pages. At step 5 of the diagnostic procedure, it wants to see a value greater than 1 megohm. I was measuring about 950Kohm, so I'm just underneath the "healthy" threshold. So, from what I know about car electronics (which isn't much) a bad ground can cause all kinds of weird and seemingly unrelated issues. So who knows....maybe all this time it was just an electrical issue that only happened when cold (ie. before the metal heats up, expands and makes a better connection somewhere so the condition goes away).

We shall see. I won't know for sure until the weather gets cold again. If this isn't it, my next step will be a complete tear down and repair of the engine wiring harness. That sounds fun!

But other than that, the car is running great. Can't wait for the tune to be finished and it's zoom zoom time.

Peace,

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Ok, so if anyone still cares, I have finally found and fixed the pesky cold weather start issue that I've been having.

First I'll say that if you live in the Detroit area, NEVER go to Hodges Subaru. They ripped me off for $1300 for changing my wiring harness which they never did. I only discovered this while doing all the other mods to the car, but there it is. Had they done what they charged me for, this problem would have been fixed long ago. But since they lied to me, I was chasing my tail on other things. On even wrote them an actual snail mail letter explaining that I discovered their deception. No reply.

Bottom line, it was the connector. In cold weather, and more recently in very humid weather as well, it would stumble and sputter on startup, wouldn't want to run and give me the P0340 code.

Once I discovered that I was lied to, I started from scratch and lo and behold, it was the connector. Repinned it and put a new housing on it and it's fixed. Thanks to iwireservices for that. 3 years later and tons of money wasted and the problem was fixed in 30 minutes with a $16 part.

https://www.iwireservices.com/

Now to finish the tune and the sleeper shall awaken.

$$$

P.S. Lots of negative reviews coming your way, Hodges. Every social media weapon I have will be aimed at your garbage dealership.

Wow, amazing... But glad you finally found the issue.

Thanks for continuing to update this thread.

Well, it looks like I spoke too soon. Sunday was a little cooler and damp in the morning and unfortunately the car was up to it's old tricks. Still sputtering and stuttering.

I'm pretty confident I'm on the right track though, based on the readings I was getting on my meter. Next I'll replace the connectors on other end of the cable in question. It's directly underneath my TMIC and it looks a little long in the tooth. Plus, any moisture that gets through my TMIC will basically spray right on top of that connector. Not the best design in the world.

Anyway, I'll replace that connector and see what I get.

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Ok....This is what I hope to be my penultimate update on this thread.

The reason for this is that, first, I just wanted to use the word "penultimate" in a sentence.

Secondly, I think I've finally found the root cause of my cold weather starting issue. I won't know for sure until I finish putting my wiring harness back together and let the car sit out in the cold overnight, but I'll know for sure this weekend if I've fixed it.

Now for the details.

First of all, as a reminder, the P0340 code is "Camshaft Position Sensor - Circuit A" fault. The "circuit A" part of that code is the tricky part. Dave over at Cryotune told me that this code is "pretty reliable". And believe he's correct. The bottom line is that the ECU sees something on the cam sensor circuit that it doesn't like and sets the code. However, I went through the entire diagnostic procedure in the manual and everything seemed ok. So after replacing multiple connectors and still no success, I decided to unwrap my entire harness so I can look for potential trouble spots on any of the three wires going to that sensor. Everything looked good. But while doing this, I found a loose connector on my passenger side TGV sensor.

Now, the 0 Volt wire (black/yellow) that comes from the cam sensor is bundled up with several other 0V wires from other sensors and goes to the ECU on a single wire. One of the sensors that share that bundle is the TGV sensor. (see picture 1).

So upon closer inspection, I saw that the TGV sensor housing was damaged. So, the connector doesn't click into place and the housing itself is gouged out (see picture 2) which could easily result in the ingress of moisture, poor connection, etc. And since this connector shares a 0V wire to the ECU, I think it may have triggered the cam sensor fault even though it's being driven by a totally different sensor.

The sucky part of course is that I can't get at it without removing the turbo, which means the down pipe has to come off too. So yeah...that's awesome. But I will know in a couple of days if this is in fact my problem. More to come very very soon. Thanks for reading.

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Wow, good find and nice write up. Thanks to you from others that may benefit from your time.

Sent from my SM-G996U using Tapatalk

Wow, good find and nice write up. Thanks to you from others that may benefit from your time.

Well, I appreciate your encouragement. Sadly, this wasn't the issue. I was so optimistic, but the car still hates the cold.

I'm going to see if my tuner (Phil at Dynotech - NZ) is willing to let me pick his brain a little about the ECU. But he's already gone over and above and has been very patient as this process has dragged on WAY too long.

If he can't offer any insight, (which I doubt) then I'm done. Very discouraged. Selling it in the spring.

$$$

P.S. On a positive note, once I sell it my wife will be a lot happier.

Well, I might as well do what I can to figure it out while the weather is cold. Who knows, maybe someone can offer some insight. I no longer think this has anything to do with the original thread, but since this topic has all my diagnostic history in it, I'll continue on. I'll be brief. (haha! no not really)

Symptoms:

1 - Cold weather ONLY (below 10 deg. C) - no code

2 - Try to start the car. Struggles and won't idle. It'll "catch" briefly but won't run. Keep trying and trying....

3 - Eventually, the CEL comes on and the engine starts right up and will idle.

4 - CODE : P0340 - Camshaft Position Sensor Circuit A.

5 - At this point, if I clear the engine code it will immediately sputter and stall and the process begins again. If I DON'T clear the code it will idle until warm

6 - as the car warms up, it is drivable and runs fairly well up to a point. It also seems to be running very rich in this state. Hard throttle will result in bogging and sputtering

7 - JUST before it gets nice and warm (optimal temperature) the car will start to sputter and want to stall again. If I'm driving at the time (ie. not stopped at a light) it will backfire a LOT. Flames out the back, the whole 9 yards. More indications of running super rich.

8 - Pull off to the side of the road and let it idle for a little more to get nice and warm (still not clearing the code). During this time, if I feather the throttle, I can keep it running. But if I hit the gas hard, it sputters. Usually this occurs at 2000 RPM and above. I will also get misfire codes on all 4 cylinders. Lots of sputtering and misfiring at this point. The neighbours probably hate me.

9 - after 20-30 minutes of idling, I can carry on it runs AWESOME. No issues at all. I can even clear the code at this point and it will NOT come back as long as the engine remains warm.

10 - On a really cold day, if I stop for say, 20-30 minutes, the engine temperature will end up just below the "sweet spot" and I'll be at about step 7 above. And the process repeats.

What I've tried:

1. New MAF sensor

2. New Temp sensor

3. New Cam Position Sensor (pasenger side - North America)

4. New Crank Position Sensor

5. New TGV Sensor (passenger side- North America)

6. New spark plugs

7. Cleaned throttle body

8. Replaced Intake gaskets with thicker ones (orange o-rings)

9. Tore apart my wiring harness and checked for anything obvious on the three wires going to my cam position sensor

10. Replaced the cam position sensor connector (repinned)

11. Replaced B20 bulkhead connector under my TMIC. This connector carries the signal wire from the cam sensor (connector housing only - did not repin)

12. Replaced TGV sensor connector (connector housing only - did not repin)

13. Went through the diagnostic procedure for the cam sensor. Stopped just short of the last step which is "Replace ECU".

14. Removed the ECU and brought it in the house to keep "warm". Then plugged it back in to the car and tried starting. No change.

15. Took ECU apart and looked for bent pins, bad solder, etc. All appears fine.

I don't think the mods are important because this issue predates the work I did on the car this summer. But here they are...

1. Catless Invidia up pipe

2. Catless Invidia down pipe

3. Invidia 3" catback

4. VF52 turbo

5. AVO TMIC

6. Grimmspeed 3-port boost controller

7. Grimmspeed cold air intake

8. Perrin turbo inlet

9. Cobb 4 bar MAP sensor

10. Tune (still in process)

Some web searches indicate that this isn't a unique problem with Subarus, but the causes seem to be varied. So my gut tells me that the code is completely misleading me and that the root cause is actually a fuel / throttle / mixture issue that is causing it to run rich / flood when cold and that throws off the cam sensor in terms of when it expects to see the signal pulse. Just a guess.

Finally...I'll add that the previous owner had put on a Viper remote start system and had apparently had the car tuned once already (which I didn't know until my tuner told me). Not sure if either of those things could have an effect.

Now, for anyone who still cares, any suggestions would be appreciated.

<3 to you all and thanks for the help so far. This is my first Subaru ever and I absolutely LOVE the car...when it's warm. My wife hates it of course, but that's only because she can't see past this issue.

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Man, I think many including myself would have torched that car by now ,with all that you have done.

What about trying a different ECU?

Sent from my SM-G996U using Tapatalk

Man, I think many including myself would have torched that car by now ,with all that you have done.

 

What about trying a different ECU?

 

Sent from my SM-G996U using Tapatalk

Well, I would consider trying that if I had one handy. Plus, it runs great when it's warm and yet still gave me trouble when the ECU itself was warm (brought it inside). So I don't think it's the ECU itself.

I've asked my tuner for help in diagnosing this, but I don't expect a reply right away. He's many time zones and an equator away. He told me that it had been tuned before and I would like to know if there's something in there that the previous owner might have done that's screwing it up in cold weather. Not sure if it would still be there after a second tune or not.

Plus, I don't know if he started with my base map that I sent him and then he changed it, or if he just grabbed a default MAP and added the appropriate changes to that.

We'll see when he gets back to me. I think he's running out of patience with me, and I can't blame him. This tuning process has dragged on for months for various reasons.

That sounds like a fueling related issue to me, either bad O2 sensors (both front and rear contribute to fuel trims, but they should be ignored on startup) OR it's a leaky injector or leaky injector o-rings that are flooding the engine. Maybe even the fuel pressure regulator, which is super complicated and you should just do an STI FPR mod.

Could also be MAF sensor or vacuum leak or injectors, but you said you looked at those already. Could also be fuel pump or more specifically the fuel pump control module. But I would look at injectors and fuel pressure regulator first.

But I would look at injectors and fuel pressure regulator first.

Thanks, CR. I'll take a look at those when I can and give an update.

If it's leaky injector o-rings, can just the o-rings be replaced (if it's even worth it)? Or am I looking at new injectors?

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I just found this thread today, as I'm getting the same CEL code on my 2006 WRX.

I've already replaced the factory fuel pressure regulator with another OEM fuel pressure regulator unit. The CEL still comes back randomly.

I already have both cam position sensors on the way in. But, I'm going to try something that I've done for every other car that I've owned - I'm going to apply dielectric grease to every plug that I touch.

I've already been told that it prohibits electrical conductivity, which is true, but it also pushes out of the way easily allowing physical connections to occur without issue. It would act as a barrier to the ingress of moisture - this helps to limit corrosion on connectors over time.

I'll give that a shot this week and report back my results.

Oh, other than a Cobb AP Stage 1 tune, my WRX is stock. I have upgraded parts like the head gaskets & head studs, a Walbro 255lph fuel pump (5 years on it). But, still on the stock turbo, stock boost, etc.

I would also try cleaning the oil control valve (OCV). That controls the cam shaft timing advance and can go bad. I had a hell of time with my outback XT and once I replaced both driver and passenger OCV and both cam shaft sensors all misfire codes went away. I only used used OEM parts as well. I hope this helps.

Thanks for sharing that tid bit of info. I hope that we don't have to go to that point as well - the money drop on parts gets rather tiring.

I am curious why this is the first that I've heard about that part in specific being a possible solution (maybe I haven't searched enough?).

10921AA080 - Valve Assembly Oil Contro

That is the OEM part number and name that I've been able to find.

https://www.subarupartsdeal.com/

Has a very nice price compared to direct from the dealership, but there are others that have virtually identical prices too, so shop around.