System Too Lean at Higher Load -- Bank 2
What does P2191 mean?
The P2191 code means the vehicle's onboard diagnostic system has detected: System Too Lean at Higher Load -- Bank 2. This is a moderate severity code.
Common Symptoms
- Hesitation during acceleration
- Lean misfire under load
- Loss of power at higher RPMs
- Poor fuel economy
- Check engine light on
Probable Causes (Ranked by Likelihood)
- Weak fuel pump losing pressure under load Very High
- Clogged fuel filter restricting fuel flow at high demand High
- Partially clogged fuel injectors on bank 2 High
- Exhaust leak before bank 2 oxygen sensor (false lean reading) Moderate
- MAF sensor underreporting airflow at higher loads Low
Step-by-Step Diagnostic Procedure
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Check bank 2 fuel trims under load -- positive LTFT above +15% during acceleration confirms lean under load
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Monitor fuel pressure during wide-open-throttle test -- pressure should not drop more than 5 PSI
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Replace fuel filter if maintenance is overdue
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Inspect exhaust manifold and connections on bank 2 for leaks that could affect O2 sensor readings
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Test fuel injector flow on bank 2 -- compare flow rates to bank 1 injectors
Frequently Asked Questions
Can I drive with code P2191?
Yes, but with reduced performance under heavy acceleration. The lean condition at higher loads can cause hesitation, misfires, and potential catalytic converter damage on bank 2. Avoid heavy acceleration and towing until repaired.
What does higher load mean?
Higher load refers to conditions where the engine is working harder -- accelerating, climbing hills, towing, or at high RPM. Under these conditions, the engine demands more fuel. If fuel delivery cannot keep up, the mixture goes lean on the affected bank.
How do I test fuel pump pressure under load?
Connect a fuel pressure gauge to the test port on the fuel rail. With the gauge visible from the driver's seat, perform a wide-open-throttle acceleration (safely). Watch the gauge -- pressure should maintain spec or rise slightly. If pressure drops during acceleration, the fuel pump is weak or the filter is restricted.