O2 Sensor Pumping Current Trim Circuit High Bank 1 Sensor 1
The P2628 code means the vehicle's onboard diagnostic system has detected: O2 Sensor Pumping Current Trim Circuit High Bank 1 Sensor 1. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $150 - $500 (parts and labor)
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Common Symptoms
- Engine running lean
- Hesitation during acceleration
- Higher exhaust temperatures
- Check engine light on
Probable Causes (Ranked by Likelihood)
- Wideband O2 sensor degraded Very High
- Short to voltage in pumping current circuit High
- Sensor contaminated by coolant or oil Moderate
- ECM O2 driver output stuck high Low
Step-by-Step Diagnostic Procedure
-
Monitor pumping current values for out-of-range high
-
Check sensor wiring for short to reference voltage
-
Inspect sensor tip for contamination
-
Test with known-good sensor if available
Frequently Asked Questions
Can oil contamination cause P2628?
Yes. Engine oil reaching the O2 sensor through valve guide wear or piston ring issues can coat the sensor element, causing inaccurate pumping current readings.
Why does P2628 cause lean running?
The high pumping current makes the ECM believe the mixture is richer than actual, so it reduces fuel delivery, causing a lean condition.
How can I tell if my O2 sensor is contaminated?
Remove the sensor and inspect the tip. A white or gritty coating indicates coolant contamination. A dark oily coating indicates oil contamination.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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