OBD Engine Oil Temperature Sensor A/B Correlation
What it means
P2C21 stands for Engine Oil Temperature Sensor A/B Correlation. P2C21 is a P code, so the fault sits in the engine, transmission and emissions systems. For P2C21, work through the cause list below, cheapest checks first.
Where it lives
For P2C21, the description names the sensor as the part involved.
What to check first
For P2C21, read the stored codes from every module, not just the engine, because related codes often name the same fault more precisely.
Check these first
- P2C21: Faulty or contaminated sensor in the fuel/air metering circuit
- P2C21: Damaged or shorted wiring or connector for the affected circuit
- P2C21: Vacuum leak or intake system restriction
- P2C21: Failing fuel pump, injector, or fuel pressure regulator
What to do next
P2C21 is a fault in the powertrain control system. The steps below are general, so what actually failed on your vehicle may not be what P2C21 names.
- P2C21: Read freeze frame data and related codes with an OBD-II scanner
- P2C21: Inspect the affected sensor wiring and connector for damage
- P2C21: Compare live sensor readings (fuel trim, airflow, temperatures) to manufacturer specs
- P2C21: Smoke test the intake system if lean or vacuum conditions are suspected
- P2C21: Replace the failed component after confirming it with live data
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Updated
Generic SAE J2012 definition. Last updated 2026-08-30.