Hello everyone, I recently purchased my first Lancer Evolution, and I've been loving it! However, I have 2 issues with the car. I'm in California, bought the car down in Corona, but brought it up to Big Bear Lake where I live, obviously a major change in altitude and temperature. Car had no codes when I bought it, however on the way up, towards the top of the mountain, it said my TCS and S-AWC systems needed to be serviced. Upon restart, they were gone, however they will come back if I'm out for a long drive at night when it's cold. Secondly, after having it up here for a few days, it started throwing CEL for the 02 sensor. If I clear it, it comes back the next day or 2 days later. I've read on these forums these issues can come from altitude and temp changes, but what can I do to fix them? I don't like having my traction control turned off, and hate seeing the CEL. I would assume changing the O2 sensor wouldn't help, not sure though. I've seen people saying spark plug foulers and extenders help or covering you O2 sensor, but they only say it when talking about test pipes or exhaust systems, my exhaust is stock. If anyone has any ideas or answers please let me know, thank you!

 

Which O2? Front or rear?
What mods are you running and which ROM?

 

I'm not sure which o2 sensor it is, I've attached what my OBD reader app says, am I able to know from what it says there? It's stock engine wise, just on wheels and lowered. I have a multimeter coming in the mail tomorrow so I can start testing the sensors and wiring and such.

 

P0137 is the Rear O2. You can try a fresh sensor if you're on the stock catalytic converter. Also, I love that your app is suggesting you buy a GM Thermostat housing to fix this!

There should also be codes for the AWC ECU if it's throwing the service message, but your app won't be able to read them. Evoscan can get you more information if you have a Tactrix cable otherwise you'll need a higher-end CANBUS scanner or a trip to the dealership.

 

Thanks for the feedback, I really appreciate it. I'm taking it to a shop up here next week where I'm guessing they'll just end up replacing the sensor, which hopefully fixes the CEL code. As far as the AWC problem, I'm unfamiliar with Evoscan. When I go to the website it's a bit confusing. Are they for tuning? Or if not what is their main purpose? And how would having one of these help me with the AWC issue?