Hi,

My 99 v6 is baffling me. I got a engine check light on when I was on a roadtrip. But it runs fine and no different from before.


I got the code scanned as a P0171 "lean bank one". I have tried cleaning the MAF (it reads properly according to the mechanic), checking for vacuum leaks, checked the fuel pressure (replaced fuel filter), replaced an O2 sensor, checked spark plugs. I had a 30K check up 5000 miles ago and I got about 140K on it. The mechanic can't figure it out.

Could the ECU be toast?

The mechanic says there is only one O2 sensor and he doesn't get how it can determine bank 1 from bank 2. I thought Bank 2 would be a different code.

You guys got a clue? I need to get it smog checked soon
Thanks

 

Search your thread title.

:wabbit2:

 

This might also be caused by a loose spark plug. I had a plug that was real tight, when it finally came out a little aluminum came out of top of the spark plug hole. Now the plug does not seal properly and oil gets into the spark plug boot and causes a the spark plug to arc in the boot, sometimes the engine light comes on. I have never checked the code, so I don't know if that code is the same as mine.

I just clean the boot and the hole and its good for another year.

 

Thanks Rabbit. I did (ok there is only one bank) and I think I have tried all the usual suspects (MAF, O2, Fuel pressure, Vacuum leak). I am looking for something beyond that.

They did check the spark plugs too.

 

there is no bank two--you are right--that means all banks are bank 1. So, overall you are running lean. Also sweep the TPS sensor and it is probably time to get your injectors cleaned and check your Idle Air Control Valve......

 

I got a new TPS when I first bought it used (I thought that would throw a different code). I cleaned the IAC valve when it started to stall on slow down (idea from searching this site .
Now mechanic just called and said they replaced the MAF and it runs much better. Crossing fingers and hope that is it.

Cleaning the injectors: how do u suggest to do this? Professionally or by throwing something in the tank

 

Update. So far the MAF and old fuel filter replacement has cleared the light and it runs and responds much better. Hope it keeps up.

The MAF did seem to respond normally to one mechanic in the shop, but the hesitation on throttle input is now gone.

 

To clean the fuel injectors your just pop them out and send them to the many different cleaning companies out there. Costs you about $150 for everything--including shipping...