Powertrain, generic (extended)

P2C3D Cylinder Head Temperature Sensor A/B Correlation

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

An engine with two head temperature sensors can check one against the other: after a long soak both should read close to each other and to coolant temperature, and while running their gap should stay inside an expected band. P2C3D means sensors A and B disagree beyond that limit although neither circuit shows a fault. No manufacturer publicly documents the code or its thresholds. From 2019, phased in until 2021, CARB asks makers that use extra component temperature sensors, also where those sensors sit in different coolant circuits, to have a monitoring plan approved. Ford's 2.7 L EcoBoost bulletins show that both PCM software and a revised CHT sensor can be to blame for implausible head readings. Compare both values on a cold engine; the one far from coolant temperature is suspect.

Likely causes

One of the two sensors has drifted out of tolerance
Contact resistance in one sensor circuit shifting its reading
Engine control software judging the pair too tightly
Real temperature difference from air pocket or poor flow in one head area

Symptoms

  • Check engine light without driveability complaints
  • Clearly different values for head temperature A and B after a cold start

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–450
Time0.5–2.5 h

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

Parts involved

cylinder head temperature sensor acylinder head temperature sensor becm

Related codes

P017BP2C39P2C38P017AP0116

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