P2274: O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 3
What to do
The car will drive normally. Ask for the harness underneath the vehicle to be inspected — it is the most exposed sensor lead on the car. And on a vehicle with two converters in series, do not let either be replaced on the strength of a monitoring reading this fault invalidates.
What this code means
The stuck-lean condition at a third sensor position on bank 1 — after a second catalyst in series, on vehicles fitted with a close-coupled converter near the manifold and a main one further back.
The reasoning is that of P2270. What the third position adds is ambiguity about which converter a monitoring fault refers to, so establishing that the sensor is at fault matters more here rather than less: on a two-converter exhaust there are two expensive parts a bad reading could be blamed on.
This is also the most exposed sensor on the vehicle, running along the underside where road spray, salt and stone damage all reach the harness. Wiring accounts for a larger share of faults at this position than at any other.
Likely causes
Start here
- Damaged wiring harness · moderate
- Faulty oxygen sensor · moderate
- Exhaust leak before the sensor · moderate
Less common
- Water ingress into connector · easy
- Corroded or loose connector · easy
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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