P0174
System Too Lean (Bank 2)
The engine is running with too much air or too little fuel on Bank 2.
Same as P0171 but for Bank 2 (the side of the engine that does not contain cylinder 1). When both P0171 and P0174 are present together, the cause is typically something that affects both banks equally, such as a MAF sensor issue, low fuel pressure, or a large vacuum leak.
Symptoms
Common Causes
Vacuum leak (both banks)
HIGHA leak at the intake manifold plenum affects both banks.
Dirty MAF sensor
HIGHMAF underreporting causes lean on both banks.
Low fuel pressure
MEDIUMWeak pump starves all injectors equally.
Bank 2 specific leak
MEDIUMIf only P0174, check Bank 2 intake runner gasket.
Step-by-Step Diagnosis
Compare fuel trims
mediumIf both banks lean, focus on common causes (MAF, fuel pressure). If only Bank 2, focus on that sides intake.
Clean MAF sensor
easyClean MAF with dedicated cleaner. Clear code and test drive.
Check fuel pressure
hardTest fuel pressure and volume at the rail.
Commonly Seen With
P0174 is frequently found alongside these codes:
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Frequently Asked Questions
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