P2236: O2 Sensor Signal Circuit Shorted to Heater Circuit Bank 2 Sensor 3
What to do
The car will drive normally. Ask for the wiring underneath the vehicle to be inspected — this is the most exposed sensor harness on the car — and do not let a converter be replaced on the strength of a monitoring reading that this fault invalidates.
What this code means
The last member of the family — the same short, at the third sensor position on bank 2, which implies a second catalyst in series on that side.
Everything about it is covered at P2233: fuelling is unaffected, rear catalyst monitoring is lost, and the harness at this position is the most exposed on the vehicle to road spray and stone damage. As with every code in this group, the reason it is worth diagnosing properly rather than clearing is that the reading it produces impersonates a failed catalytic converter.
Likely causes
Start here
- Damaged wiring harness · moderate
- Internal short in the oxygen sensor · moderate
- Water ingress into connector · easy
Less common
- Incorrectly wired universal oxygen sensor · moderate
- Melted wiring against the exhaust · 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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- The car — make, model, year and engine. The same fault behaves differently on each.
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