P2629: O2 Sensor Pumping Current Trim Circuit/Open Bank 2 Sensor 1
What to do
The car will drive normally and use a little more fuel, with emissions monitors not completing.
Ask for the two banks' sensors to be compared on a scan tool — they are identical parts doing identical jobs, so comparing them directly is the quickest way to tell whether this one is genuinely out of calibration, and it costs nothing.
The warnings at P2626 apply: this sensor cannot be tested by looking for a switching voltage, and its connector must not be replaced with one from another sensor because the calibration lives in it.
What this code means
An open circuit in the pumping current trim of the upstream oxygen sensor on bank 2. The mechanism, and the two warnings that matter more than the diagnosis, are at P2626.
On a vehicle with two banks, one useful comparison is available for free: bank 1's sensor. Identical parts in identical roles, so the two sets of live data should broadly agree, and a scan tool showing them side by side tells you quickly whether the calibration on this bank is genuinely astray. That is a stronger test than anything that can be done with a meter on a single sensor, and it costs nothing.
Bank 2 is worth checking for one practical reason too. On a transverse V engine it is usually the bank against the bulkhead — hotter, harder to reach, and with a loom routed through a tighter, hotter space. Heat-related wiring failures are correspondingly more common there than on bank 1, so a run of sensor faults confined to one bank is often about where it sits rather than about the part.
Likely causes
Start here
- Corroded or loose connector · easy
- Open circuit in sensor wiring · moderate
- Faulty oxygen sensor · moderate
- Heat damage to sensor or wiring · moderate
Less common
- Damaged calibration resistor in connector · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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