Powertrain, generic (extended)

P2C3C Cylinder Head Temperature Sensor B Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2C3C is stored when the head temperature signal of sensor B drops out briefly or jumps in steps that no mass of hot metal could follow, while the samples on their own may still lie within the valid window. Loose terminals, a wire that touches ground only over bumps or with engine movement, corrosion in the plug and a cracked thermistor are the usual culprits. No manufacturer publicly documents P2C3C; Ford's bulletins for this sensor family deal with P2C38 and P2C39 and point to PCM software. California rules require engine component temperature sensors used for emission control to be monitored much like the coolant sensor. Wiggling harness and plug while watching live data is the most revealing check. A fault that stays low or high stores P2C3A or P2C3B instead.

Likely causes

Loose or spread terminal in the sensor B connector
Harness rubbing on engine parts and shorting only at times
Corrosion in the plug
Cracked sensor element

Symptoms

  • Check engine light that comes and goes
  • Jumping head temperature B in live data
  • Occasional fan runs or brief warnings without real overheating

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–350
Time0.5–2.5 h

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

Parts involved

cylinder head temperature sensor bwiring harnessecm

Related codes

P2C38P2C3AP2C3BP2C39P017E

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