A failed wideband oxygen sensor on Bank 2 Sensor 1, where the internal pumping cell or heater circuit has degraded; Corroded, chafed, or shorted wiring in the sensor's pumping current trim circuit, often near the exhaust manifold or connector; A poor electrical connection at the sensor pigtail or the engine control module harness, causing high resistance; Contamination of the sensor tip from coolant, oil, or silicone, which alters the pumping current draw; An exhaust leak upstream of the sensor that allows outside air to skew the reading and force the trim high; A rare internal fault in the engine control module's sensor driver circuit

DTC codes / P26xx · Computer and output circuits / P2631

P2631O2 Sensor Pumping Current Trim Circuit High (Bank 2 Sensor 1)

P2631 means the engine control module has detected that the electrical current trim signal for the oxygen sensor's pumping circuit on Bank 2 Sensor 1 is higher than the expected range. This sensor is a wideband air-fuel ratio sensor, and the pumping current trim is a calibration value the module uses to fine-tune the sensor's accuracy; a high reading indicates the circuit is drawing too much current or the signal voltage is stuck high.

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 symptoms besides the warning light
A slight decrease in fuel economy as the module defaults to a richer air-fuel mixture
Occasional rough idle or hesitation during acceleration if the sensor signal is skewed
A failed emissions test due to an incorrect air-fuel ratio reading
In rare cases, a noticeable loss of power or surging under light throttle

Common causes, most likely first

A failed wideband oxygen sensor on Bank 2 Sensor 1, where the internal pumping cell or heater circuit has degraded
Corroded, chafed, or shorted wiring in the sensor's pumping current trim circuit, often near the exhaust manifold or connector
A poor electrical connection at the sensor pigtail or the engine control module harness, causing high resistance
Contamination of the sensor tip from coolant, oil, or silicone, which alters the pumping current draw
An exhaust leak upstream of the sensor that allows outside air to skew the reading and force the trim high
A rare internal fault in the engine control module's sensor driver circuit

How to diagnose and fix it

Inspect the Bank 2 Sensor 1 connector and wiring for corrosion, chafing, or loose pins, and clean or repair as needed
Check the sensor's heater circuit resistance and compare it to the manufacturer's specification to rule out a failed heater
Perform a voltage drop test on the pumping current trim circuit to confirm whether high resistance is in the wiring or the sensor
Use a scan tool to view live data for the Bank 2 Sensor 1 pumping current trim and compare it to the Bank 1 sensor to see if the reading is plausible
Smoke-test the exhaust system upstream of the sensor to rule out leaks that can skew the trim value
Replace the Bank 2 Sensor 1 wideband oxygen sensor if wiring and exhaust checks pass but the trim remains high
Clear the code and perform a drive cycle to verify the repair, then recheck for pending codes

Before you replace the Bank 2 sensor

A high pumping current trim reading is often caused by a contaminated sensor tip from an internal coolant leak or excessive oil consumption, so fixing the root cause matters more than swapping the sensor alone.
Technicians sometimes misdiagnose this code as a catalytic converter fault because a skewed oxygen sensor reading can mimic a rich or lean condition, but the converter is rarely the culprit for P2631.
The pumping current trim circuit is sensitive to voltage drops, so a battery or charging system that is weak can set this code intermittently without any sensor fault at all.
On some vehicles, the Bank 2 Sensor 1 connector is located close to the exhaust manifold and suffers heat damage that creates high resistance only when the engine is hot, so wiggle-test the harness while watching live data.
Replacing the sensor without checking for exhaust leaks upstream can lead to a repeat code because the leak causes the new sensor to trim high as well.

Can I keep driving with P2631?

You can usually continue driving with P2631, but avoid heavy acceleration or towing until it is repaired because the engine may run richer than normal and reduce fuel economy. Have the fault diagnosed soon to prevent long-term damage to the catalytic converter from an uncorrected rich condition.

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.