Powertrain, generic (extended)

P2C3B Cylinder Head Temperature Sensor B Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

With P2C3B the voltage from cylinder head temperature sensor B stays above the valid ceiling, which the module would have to read as a head far colder than any real engine. An interrupted signal wire, a lost sensor ground, a terminal that has backed out of the plug or a thermistor cracked by heat cycling are the typical finds. No manufacturer publicly documents the code. For sensor A, Ford's 2024 OBD summary sets the high-input code above 4.96 V lasting 5 s. With the head temperature gone, the engine control falls back on coolant temperature or a default, may run the fans as a precaution and can keep warm-up settings longer than needed. Measure the voltage at the unplugged sensor first. The ground short case is P2C3A, the general circuit fault P2C38.

Likely causes

Open signal wire or terminal pushed out of the connector
Sensor return (ground) circuit open or high resistance
Thermistor of sensor B broken internally

Symptoms

  • Live data shows head temperature B at the lowest possible value
  • Check engine light
  • Fans run more often, idle and warm-up behaviour unusual

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–350
Time0.3–2 h

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

Parts involved

cylinder head temperature sensor bwiring harnessecm

Related codes

P2C38P2C3AP2C39P2C3CP017D

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