P2628: O2 Sensor Pumping Current Trim Circuit High Bank 1 Sensor 1
What to do
Normal driving, slightly worse economy, and emissions monitors that will not complete.
If any exhaust work has been done — a manifold, a downpipe, a catalytic converter, a flexi pipe — mention it immediately. This sensor has to be unplugged for all of those, and a plug left disconnected or reconnected to the wrong sensor is the commonest cause in that situation. That is a free fix. On an engine with a sensor on each bank, swapped connectors matter more than they look, because each carries its own calibration and they are not interchangeable.
What this code means
The pumping current trim circuit reads above its valid range on the bank 1 upstream sensor — an open circuit, a disconnected connector, or a short to supply. The mechanism is at P2626.
An unmated connector is a leading cause and has an obvious trigger: this sensor is removed for exhaust work. A manifold, a downpipe, a catalytic converter or a flexible section all mean unplugging it, and the plug is often left tucked out of the way and forgotten, or reconnected to the wrong sensor on an engine that has one per bank. A trim code appearing straight after exhaust work is a connector before it is anything else — and if the vehicle has two upstream sensors, swapped plugs are worth ruling out at the same time, because each carries its own calibration and the two are not interchangeable.
Likely causes
Start here
- Disconnected sensor connector · easy
- Open circuit in sensor wiring · moderate
- Corroded or loose connector · easy
Less common
- Faulty oxygen sensor · moderate
- Wiring shorted to voltage · moderate
Symptoms
Components involved
Information, not instruction
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Community experience
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