Canadian Hummer Club Forums

System too lean bank 1. Why the heck mechanic miss out? How mechanic can let go this and said don't worry if the engine light will cone up. Just ignore it. ?

I would suggest getting it fixed as this code will eventually cause damage to the catalytic converter.

 

Here is the list of possible causes for that code;

 

A code P0171 may mean that one or more of the following has happened: The MAF (Mass Air Flow) Sensor is dirty or faulty Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry. There could be a vacuum leak downstream of the MAF sensor Possible cracked vacuum or PCV line/connection Faulty or stuck open PCV valve Failed or faulty oxygen sensor (bank 1, sensor 1) Sticking/plugged or failed fuel injector Low fuel pressure (possible plugged/dirty fuel filter!) Exhaust leak between engine and first oxygen sensor


Read more at: https://www.obd-codes.com/p0171
 
 
 

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The most common would be an intake gasket leak or exhaust manifold leak on the drivers side.
 
The sensor could also be defective but I suspect it to be more likely a leak.
 
Hope this helps,
 
Kev