Cause
Damaged or distorted connector terminal
A terminal inside a connector that has been bent, spread or pushed back in its housing, so the joint no longer grips. It is distinct from corrosion because the metal is clean — the failure is mechanical, and every visual check of a bright, dry connector passes it.
Probing is a leading cause, which is worth admitting. A test probe forced into the front of a female terminal spreads it permanently, so a connector that was fine before diagnosis is marginal afterwards, and the fault appears to move as work proceeds. Back-probe from the wire side or use the manufacturer's test leads, never the front of the terminal.
The other version is a terminal backed out of its housing. It looks fully seated from outside while sitting a few millimetres short of contact, so the circuit works until vibration or temperature separates it — the classic intermittent that will not reproduce on a bench. Pull gently on each wire behind the connector, which finds a backed-out terminal immediately, and check the lock is engaged before blaming the harness.
Typically an easy fix. Often worth checking before paying anyone to look.
Codes this can cause (4)
Codes where this is a likely explanation first, rather than merely a possible one.
- P2239 O2 Sensor Positive Current Control Circuit High Bank 1 Sensor 1 Likely for this code High
- P2242 O2 Sensor Positive Current Control Circuit High Bank 2 Sensor 1 Likely for this code High
- P2231 O2 Sensor Signal Circuit Shorted to Heater Circuit Bank 1 Sensor 1 High
- P2234 O2 Sensor Signal Circuit Shorted to Heater Circuit Bank 2 Sensor 1 High
Information, not instruction
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