System Too Lean at Higher Load

What it means

P2191 is stored when the oxygen sensor reports more oxygen in the exhaust than expected and the long-term fuel trim reaches its positive limit. The engine is getting too much air or too little fuel.

This entry is compiled automatically from the standard definition and typical diagnostic practice for this type of fault. A detailed, reviewed article is in preparation.

Symptoms

• Check engine light on
• Rough or unstable idle
• Hesitation or poor acceleration
• Increased fuel consumption
• Possible limp mode with reduced power

Common causes

1. Vacuum or intake leak after the air flow sensor
2. Dirty or failing mass air flow sensor
3. Low or high fuel pressure
4. Leaking, clogged or stuck injector
5. Faulty upstream oxygen sensor or exhaust leak near it

How to diagnose

1. Watch short- and long-term fuel trim at idle and at 2500 rpm to see whether the fault is load dependent
2. Smoke test the intake for vacuum leaks
3. Clean or test the mass air flow sensor
4. Check fuel pressure under load and injector balance
5. Inspect the exhaust manifold and upstream oxygen sensor area for leaks

Terms to know

Related codes

Nearby codes in this group

• P2190System Too Rich at Idle
• P2192System Too Rich at Higher Load
• P2189System Too Lean at Idle
• P2193System Too Lean at Higher Load
• P2188System Too Rich at Idle
• P2194System Too Rich at Higher Load
• P2187System Too Lean at Idle (Bank 1)
• P2195O2 Sensor Signal Stuck Lean