I have seen this problem develop from a tune. What caused it was a poor match of injector sizings & latency to what the car wants. With a P171 your low & mid fuel trims are probably whack. IIRC, a P171 can also be tripped if your STFT values end up maxing out for too long.

Generally the problem is poor injector scaling and injector latencies. With EvoScan or Mitsulogger and a Taxtrix cable you can see what your ECU is trying to do. Well worth the investment and time to learn.

 

I've also been throwing the P0171 code for a few months or so, but my last tune was at least a year ago. I tried cleaning the MAF sensor, no joy. I've been told to try lucas fuel injector cleaner and I'm about to use that once I fill up my gas tank. Was thinking it could be the o2 sensor, but don't want to spend the $ to find out that wasn't it and I don't seem to have any leaks in my lines.

MAIN QUESTION... is driving the car with this SES code bad? I don't see/hear/feel a difference in my car.

 

For what it's worth, I had the same code on my 06 MR for a while, and finally took it to a tuner to look at. They discovered it was the factory fuel pressure regulator. Once we installed an aftermarket regulator with a gauge for setting it to the right pressure, I haven't thrown a code once.

Something worth checking into...

 

Thanks!

 

did this fix it?
its 2019 and I’m having the code pop up.