Powertrain, generic · Fuel and air metering

P0199 Engine Oil Temperature Sensor A Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

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.

Likely causes

Loose contact or corroded pins at the sensor connector
Harness chafing intermittently (engine movement)
Sensor with internal hairline crack
Control module ground connection

Symptoms

  • Check engine light or only a stored code
  • Oil temperature reading jumps
  • Occasionally restricted cam timing

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–250
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

engine oil temperature sensorsensor wiring

Related codes

P0195P0196P0197P0198P01BD

References: law.cornell.edu, fordservicecontent.com, saabwisonline.com.