P2191
System Too Lean at Higher Load (Bank 1)
Bank 1 fuel trim hits the lean limit only at higher engine load. Pattern points to a fuel-supply restriction — failing fuel pump, blocked filter, or weak injectors — rather than a vacuum leak (which would dominate at idle).
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Rough idle, possible stalling
- Hesitation or hard cold start
- Power loss under load
Common causes
Ordered by how often each turns out to be the cause.
- Fuel pump weak under loadCommon
- Fuel filter cloggedPossible
- MAF reads low at high airflowPossible
Parts involved
- Fuel Pump
- Fuel Filter
- Fuel Injector
- Mass Air Flow Sensor
P2191 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.