What Does P2191 Mean?
The PCM detects an excessively lean air/fuel mixture on Bank 1 cylinders during higher engine load conditions (acceleration or heavy throttle). The oxygen sensors indicate insufficient fuel or excess air when more power is demanded.
Common Causes
30%
Restricted or clogged fuel filter reducing fuel flow under high demand
25%
Weak fuel pump unable to maintain adequate pressure during high load
20%
Vacuum leaks in intake manifold becoming more pronounced under load
15%
Clogged or restricted fuel injectors on Bank 1 cylinders
10%
Faulty MAF sensor under-reporting airflow at higher engine loads
Diagnostic Steps
1
Step 1: Monitor fuel pressure under load conditions using a fuel pressure gauge during road test or dynamometer test
2
Step 2: Check long-term and short-term fuel trims on Bank 1 at various engine loads (should show high positive values)
3
Step 3: Perform fuel volume delivery test to verify pump output meets specifications
4
Step 4: Inspect intake system for vacuum leaks using smoke test or propane enrichment method
5
Step 5: Test fuel injector spray patterns and flow rates on Bank 1 cylinders
Estimated Repair Cost
$200 - $1,200
Parts + labor, varies by vehicle and location
The PCM detects an excessively lean air/fuel mixture on Bank 1 cylinders during higher engine load conditions (acceleration or heavy throttle). The oxygen sensors indicate insufficient fuel or excess air when more power is demanded.
The most common cause of P2191 (System Too Lean at Higher Load Bank 1) is: Restricted or clogged fuel filter reducing fuel flow under high demand
Typical repair costs for P2191 range from $200 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Moderate safety concern due to reduced power during acceleration and potential engine hesitation during passing maneuvers. May cause engine overheating under sustained high load.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2191 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Delivery System
Difficulty
Type
Generic (SAE)
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