Powertrain, generic · Fuel and air metering

P012F Engine Coolant Temperature / Engine Oil Temperature Correlation

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P012F compares the coolant temperature sensor with the engine oil temperature sensor. The documented user is Ford's Power Stroke diesel. After a calibration update for the 6.0 litre engine, Ford uses it to monitor oil cooler efficiency: if the oil gets much hotter than the coolant at certain speed and load, the oil-to-coolant heat exchanger is probably clogged, and P012F sets together with the wrench lamp. On the 6.7 litre (2015–2018) several bulletins treat P012F as a false setting – partly below 5 °C ambient – cured by reprogramming the engine module. Ford's 2023 diesels run the cold-start comparison of coolant against oil temperature (35 °C limit after 6 h) under P0196 instead. GM does not use the code, and the code does not say which sensor or which system is at fault.

Likely causes

Oil cooler (oil-to-coolant heat exchanger) clogged – oil much hotter than coolant
Engine module software (false setting, especially in cold weather)
Coolant or oil temperature sensor inaccurate, or its wiring faulty
Thermostat stuck open or low coolant
Block heater in use (only coolant preheated)

Symptoms

  • Check engine light and/or wrench lamp (Ford)
  • Raised oil temperature with a clogged oil cooler
  • Often no driving symptoms when software is the cause

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–2,500
Time0–10 h

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

Parts involved

engine coolant temperature sensorengine oil temperature sensoroil cooler

Related codes

P0196P0116P0128P011BP008FP0197

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.