P0240

Hey LGT,

 

My Stage II (mickeyD) Outback just started throwing P0240. LearningView says this is a cat inefficiency code. A couple weeks ago I did remove my equal length headers and put the stock manifolds back on and replaced the front o2 sensor but other than that the car has been in the same state for the past year. CNT catted downpipe, no-cat uppipe, stage II tune, etc.

 

Isn't there a way to bypass this through open-source tuning? I searched the forums here, at RomRaider and Taxtrix for P0240 and didn't have any luck finding the information.

 

I also understand that de-foulers or sparkplug spacers are used sometimes to help this situation, but I need to resolve it by Monday (don't ask, please)

 

Thanks!

if its the up pipe sensor do the resistor mod if thats what the code is, the resistor tricks the computer as false positive

Whoops! It's actually the code P0420, not P0240 which I posted in the topic title and the first post. I'm doing some reading and it looks like this has been described before (http://www.scoobypedia.co.uk/index.php/Knowledge/DisableSubaruFaultCodes). I'll post back whether it works for me.

 

In the mean time, I cleared the ECU with learningview and took it for a half-hour drive. Learningview shows no temp or learned DTCs yet

You can disable the code through romraider and ecuflash. in the map, when you open it up through romraider, on the lefthand column it will say diagnostic trouble codes, expand that and find p0420, click it, uncheck Enable. save, and reflash.

 

I'm assuming you need an inspection for october but this code should be taken seriously.

 

you're running lean which could intake a vac leak, like a post-maf one, check all the tubes and hoses and hose clamps to find if any popped off. air that is sucked in after the maf will cause the AFR to lean out a bit and your o2 sensors will pickup on it and throw a 420.

Hey BMX,

 

Thanks for the info. I was able to successfully flash the new ecu file using ECUflash. I haven't gotten ECU flash to work on 7 yet, so I just swapped in an old hard drive with ECUflash already setup on XP.

 

I thought that the cat inefficiency code worked off the downstream/rear o2 sensor. Why would this read faulty if I'm running lean? I can pull some lambda figures off the front o2 to make sure but I didn't know that this could show up on the rear sensor.

Woops. I brain farted big time, i dont know why i thought it was a lean code sorry. Either way you're right, the rear o2 is used to confirm exiting 02 content. Most tuners disable that code all together as some high flow cats still make it throw that code.