Faulty wideband oxygen sensor (Bank 1 Sensor 1) with an internal short or degraded pumping cell; Contaminated sensor element from oil, coolant, or silicone poisoning; Damaged or corroded wiring in the sensor pumping current circuit; Poor electrical connection at the sensor or ECM harness; Exhaust leak upstream of the sensor affecting its reading; ECM internal driver fault on the pumping current circuit (rare)

DTC codes / P26xx · Computer and output circuits / P2628

P2628O2 Sensor Pumping Current Trim Circuit High (Bank 1 Sensor 1)

P2628 indicates that the engine control module has detected an abnormally high current trim value in the oxygen sensor pumping circuit for Bank 1 Sensor 1, which is the upstream wideband air-fuel ratio sensor. The computer commands a specific pumping current to maintain the sensor's reference voltage, and the trim needed to achieve that target has exceeded the calibrated high limit.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaComputer and output circuits

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Slightly rough idle or hesitation during acceleration in some cases
A drop in fuel economy if the sensor feedback becomes biased
Occasional lean or rich running conditions that may trigger other codes
Failed emissions test due to incorrect air-fuel ratio feedback

Common causes, most likely first

Faulty wideband oxygen sensor (Bank 1 Sensor 1) with an internal short or degraded pumping cell
Contaminated sensor element from oil, coolant, or silicone poisoning
Damaged or corroded wiring in the sensor pumping current circuit
Poor electrical connection at the sensor or ECM harness
Exhaust leak upstream of the sensor affecting its reading
ECM internal driver fault on the pumping current circuit (rare)

How to diagnose and fix it

Inspect the sensor wiring and connector for damage, corrosion, or loose pins, and repair as needed
Check for exhaust leaks between the engine and the sensor that could skew readings
Measure the sensor heater resistance and compare to specification to rule out a failed heater
Perform a live data check of the pumping current trim and compare to expected values under different conditions
Replace the Bank 1 Sensor 1 wideband oxygen sensor if wiring and exhaust are intact
Clear the code and verify the repair with a test drive and live data monitoring
If the code persists, diagnose the ECM driver circuit or replace the ECM as a last resort

What the pumping current trim really tells you

A high trim value often means the sensor is working harder to maintain its reference voltage, which can be caused by a lean exhaust condition rather than a dead sensor.
Many technicians replace the sensor only to find the code returns because a small exhaust leak upstream was the real culprit.
The pumping current trim is a calculated value, so a weak battery or charging system issue can cause false readings on some vehicles.
This code is specific to wideband air-fuel ratio sensors, not traditional narrowband oxygen sensors, so parts lookup must match the sensor type.
Clearing the code without addressing the root cause may lead to a repeat failure and wasted expense on unnecessary sensor replacements.

Can I keep driving with P2628?

You can usually continue driving with this code, but avoid aggressive acceleration or heavy loads until it is diagnosed, as the engine may be running with a biased air-fuel ratio that can affect emissions and fuel economy.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.