P0199: Engine Oil Temperature Sensor A Circuit Intermittent/Erratic
What to do
Usually driveable. Report that the fault comes and goes.
What this code means
The oil temperature signal is unstable rather than steadily wrong, completing the P01xx range. Harness and connector faults dominate; wiggle-testing while watching live data is far more productive than static measurement.
Likely causes
Start here
- Intermittent wiring fault · moderate
- Corroded or loose connector · easy
Less common
- Chafed harness against engine or bracket · moderate
- Faulty engine oil temperature sensor · 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
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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