P0199 code meaning
Engine Oil Temperature Sensor A Circuit Intermittent/Erratic
Powertrain system Generic code P01xx codes Check engine light
What P0199 means
The engine oil temperature sensor A is an NTC thermistor fed with 5 V through a resistor: the hotter the oil, the lower the signal voltage. The engine module uses the oil temperature for variable cam timing (Ford disables it with cold oil or a sensor fault), engine protection and the oil life monitor; many engines have no such sensor and use a calculated oil temperature instead. P0199 covers brief or erratic signal faults: the value jumps faster than oil temperature can physically change, or a circuit fault appears only momentarily – typically a loose contact. No manufacturer document with thresholds for P0199 was found; GM and Ford catch short faults with counting windows under P0197/P0198. The description rests on CARB's circuit monitoring requirement and component information.
P0199 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P0199
- Check engine light or only a stored code
- Oil temperature reading jumps
- Occasionally restricted cam timing
Common causes of P0199
- Most likelyLoose contact or corroded pins at the sensor connector
- PossibleHarness chafing intermittently (engine movement)
- PossibleSensor with internal hairline crack
- Less likelyControl module ground connection
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Engine oil temperature sensorSensor wiring
What each part of P0199 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1 | Area: fuel and air metering. |
| 99 | The exact fault in that area. |
What to do next
- Note P0199 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0199
What does P0199 mean?
P0199 means "Engine Oil Temperature Sensor A Circuit Intermittent/Erratic". The engine oil temperature sensor A is an NTC thermistor fed with 5 V through a resistor: the hotter the oil, the lower the signal voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with P0199?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0199 fail an emissions test?
Yes, it can. P0199 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0199 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0199 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.