Jump to content
LegacyGT.com

98 OBL: P1507 solved (finally...)


Recommended Posts

Hi folks,

 

Since September I've been wrestling with a difficult P1507 that causes my car to stall out while decelerating downhill, and idle very roughly (undrivable) when I restart the car. I took a systematic approach to troubleshooting it, replacing one thing at a time to try and isolate what was causing the P1507. After two months of DIY, I finally solved it.

 

What fixed it: replacing the vehicle speed sensor.

 

What did not fix it (but probably was good for the car):

- new spark plugs + wires

- new fuel filter

- new air filter

- new neutral safety switch

- cleaning the IACV

 

In exchange for fixing the P1507 by replacing the VSS, I now have a new P0325 (knock sensor) CEL code that I didn't have previously. But at least my car runs now and doesn't stall out while decelerating.

 

Thanks to everyone for providing different tips and advice. P1507 is a real b*%#h, but taking a systematic DIY approach paid off in the end.

 

ps- Sometimes when I replace switches and sensors, I wonder if they were in fact bad. In the case of my VSS, there was no question- the 'key' (paddle-like metal rod sticking out the end) was completely broken, and floating loosely inside the sensor housing. It had broken off of its base after ~130k miles.

Link to comment
Share on other sites

P1507 ???

 

that's evap, right??

what year?

what engine?

what trans?

 

i think one of the things you removed and reconnected when replacing the speed sensor (auto trans?),

corrected the problem.

probably a small vac hose going to the strut tower,

or the small filter in the small vac hose,

or something like that.

 

the ''spade tongue'' on the end of the speed sensor is supposed to be loose.

at least all of the ones i have seen on my auto trans cars have been.

 

i'm glad you car is running better,

but i doubt ti is due to the new speed sensor.

Link to comment
Share on other sites

P1507 ???

 

that's evap, right?? what year? what engine? what trans?

 

i think one of the things you removed and reconnected when replacing the speed sensor (auto trans?), corrected the problem. probably a small vac hose going to the strut tower, or the small filter in the small vac hose, or something like that.

 

the ''spade tongue'' on the end of the speed sensor is supposed to be loose.

at least all of the ones i have seen on my auto trans cars have been.

 

i'm glad you car is running better, but i doubt ti is due to the new speed sensor.

 

Hi, and thanks for the note. My car is a 98 OB Legacy, manual trans with a 2.5L. Sorry I didn't mention this (I have on previous posts on my P1507 problem). My main problems were having a recurring P1507 code that very effectively disabled my car (it would cause it to stall out when decelerating downhill), after restarting, the idle was so rough it was un-drivable until I used a code-reader to erase the code. I could repeat this as often as I wished to, just by driving down a hill. My other issue at the time was that my speedo quit working.

 

In hindsight, I probably should have focused on that fact that my speedo quit and pursued this angle, but at the time I focused on finding solutions to what causes a P1507, and unfortunately there appear to be many causes.

 

(moral of the story: if your speedo craps out and the tach still works, replace the VSS pronto).

 

P1507 is described as 'Intake Air control'. While I am certainly not a 'seasoned guru' when it comes to DIY fixes on my OB, I am very confident that in this case that (1) My vehicle speed sensor (VSS) was indeed broken, and (2) replacing the VSS directly solved the P1507 error code.

 

(1) VSS being broken: the 'key' (spade tongue) on my original VSS was not only loose, it had clearly broken from its base inside the sensor housing body. The 'key' on my new sensor was indeed somewhat loose, but its orientation was always parallel to the sensor body. In my bad VSS, the part of the 'key' that sticks out now hangs down at a ~45 degree angle from the sensor housing body. Its clear that it broke-off at the base and now floats freely in the housing (the 'key' must have a flanged end on it, as I can't pull it out of the sensor housing). In short, its toast.

 

(2) I am convinced that replacing the VSS is what actually solved my P1507 problem for two reasons:

 

- I went through, methodically, all the other repair and replacement suggestions that are suggested to fix P1507. This includes new plugs/wires, new air/fuel filter, neutral safety switch, cleaning IACV, checking for vac leaks, etc. The key observation is that I did each of these steps one at a time, and verified after each step that the P1507 was still present; I didn't combine any r/r steps, as I wanted to try and detect where the problem was located. After all of the above, I could still reliably (like clock-work) force my car to throw a P1507 code simply by decelerating downhill. The point is that none of this prevented P1507.

 

- The day I replace the VSS, that is absolutely all I did to my car other than to put it on jack stands. I didn't touch anything else (no other plugs, hoses, etc), other than use a 17 mm wrench to replace the sensor and unplug the sensor plug. After I installed the new VSS, my speedometer worked immediately, and I have not experienced a single engine stall or P1507. I've now driven my car into town and back (~30 miles), and do not get the P1507.

 

Based on the above reasoning, it seems clear to me that replacing the VSS directly solved both my non-functioning speedo issue, and also my car-disabling P1507 problem. I won't claim to know all the subtleties of what causes P1507 error codes, but I think a strong case can be made based on my experience that the VSS should be included in the 'family' of possible solutions when faced with a difficult P1507. Hopefully this might help others who encounter this.

 

Again, many thanks for your comment. I offer all the detail above in an effort to clarify what I did and how I did it for others who might be interested. It took me two months to solve this, which I wish was shorter, but it was mostly because I can only work on the OB on the weekends, and I have to wait ~7 days for replacement parts to arrive to where I live in Puerto Rico. If I lived near a parts house, I'm guessing I could have figured this out in one or two weekends, but oh well.

 

Cheers, Aaron

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.



×
×
  • Create New...

Important Information

Terms of Use