Lack of HO2S Switch -- Sensor Indicates Lean -- Bank 2 (Ford)
What does P1151 mean?
The P1151 code means the vehicle's onboard diagnostic system has detected: Lack of HO2S Switch -- Sensor Indicates Lean -- Bank 2 (Ford). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Engine running lean on bank 2
- Rough idle or misfire on bank 2 cylinders
- Poor acceleration
- Lean surge or stumble
Probable Causes (Ranked by Likelihood)
- Vacuum leak on bank 2 side of intake Very High
- Faulty or lazy front oxygen sensor -- bank 2 High
- Low fuel pressure Moderate
- Exhaust leak before front O2 sensor -- bank 2 Moderate
- Clogged fuel injector on bank 2 Low
Step-by-Step Diagnostic Procedure
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Perform a smoke test to check for vacuum leaks on bank 2
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Monitor O2 sensor voltage on bank 2 -- should switch between 0.1V and 0.9V
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Check fuel pressure at idle and under load
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Inspect exhaust manifold on bank 2 for cracks or leaks
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Perform a fuel injector balance test on bank 2 cylinders
Frequently Asked Questions
Can I drive with code P1151?
You can drive short distances, but a persistent lean condition can damage the catalytic converter. The bank 2 catalytic converter can overheat from the lean misfire.
What causes P1151?
Vacuum leaks on the bank 2 side of the intake are the most common cause. Ford vehicles with plastic intake manifolds are known for developing cracks over time.
How do I identify bank 2 on my Ford?
On Ford V6 and V8 engines, bank 2 is the side that does not contain cylinder 1. On the 4.6L and 5.4L V8, bank 2 is the driver side. On the 3.5L V6, bank 2 is the rear bank near the firewall.