5 replies to this topic

[Dylan720]

Hi all so I finally got my suby back on the Rd today after a engine swap and few small issues that have now all been sorted she's driving like a brand new car again but I keep getting 2 codes p0171 system too lean bank 1 and p0174 system too lean bank 2. I can clear the codes and drive the car all day and it don't come back on but when I turn the car off then back on a few minutes after driving it comes back on again. There seems to be no change at all in the engine not running raugh or sluggish or missing still very smooth same power so not to sure what could be causing it. Any help would be great

[duncanm]

ECU is trying to add excessive amounts of fuel to get the lambdas in the right range.  H6 has an O2 sensor on each exhaust, so something common to the two banks.

 

Intake leaks (excess air), fuel pressure low, temperature sensor etc.   Go through the list in the FSM.

 

I wonder if the fact it occurs early (cold engine) points to anything?

[Dylan720]

It does it hot and cold I drove for 2 hours turned it of then started it 5 minutes later then after driving for a couple of minutes the light came on again I cleared it then last night it was cold hadent driven it for a good 3 to 4 hours and after a minute or 2 the light came on again so seems to be both hot and cold but still seems to run perfect

[El_Freddo]

How old are the O2 sensors?

Sounds like they might not be heating up as expected. Just a guess.

Cheers

Bennie

[allpaw4]

Oxy sensor heaters are renowned for dying in the H6 models. I've got stored codes for both of my front ones still.

[Dylan720]

Ide say they would be the original ones can they cause that lean code to come on I thought oxy sensor had a different code and would say oxy sensor not lean on bank 1 and bank 2