Air-Fuel Ratio Sensor Slow Response -- Bank 2 Sensor 1 (Honda)
What does P1166 mean?
The P1166 code means the vehicle's onboard diagnostic system has detected: Air-Fuel Ratio Sensor Slow Response -- Bank 2 Sensor 1 (Honda). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Poor fuel economy
- Slight hesitation during acceleration
- Failed emissions test
- Engine may run slightly rough
Probable Causes (Ranked by Likelihood)
- Aging or worn air-fuel ratio sensor -- bank 2 Very High
- Exhaust leak before the sensor on bank 2 High
- Oil or coolant contamination of the sensor Moderate
- Wiring issue at the sensor connector Moderate
- Engine running excessively lean or rich on bank 2 Low
Step-by-Step Diagnostic Procedure
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Monitor air-fuel ratio sensor response time with a scan tool
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Check for exhaust leaks on bank 2 -- exhaust manifold and connections
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Inspect sensor wiring and connector for damage or corrosion
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Check for engine oil or coolant leaks that could contaminate the sensor
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Verify no other DTCs are affecting fuel delivery to bank 2
Frequently Asked Questions
Can I drive with code P1166?
You can drive short distances. The engine may have slightly reduced fuel economy and performance. Have the sensor replaced at your next service appointment.
What causes P1166 on Honda?
An aging air-fuel ratio sensor that responds too slowly is the most common cause. Honda V6 engines can also develop exhaust leaks at the flex pipe that affect sensor readings.
Can I replace the sensor myself?
Yes. The bank 2 front sensor on Honda V6 engines is typically accessible from the top of the engine. Use an O2 sensor socket and apply penetrating oil to the threads before removal.