P2C3B

Code

Generic P — Powertrain

Cylinder Head Temperature Sensor B Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 23 EN: 34 RU: 19

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Read freeze‑frame and permanent data and confirm P2C3B is current
Scan live data: compare CHT sensor B reading to sensor A (if present) and to ambient/engine temp expected values
Visual inspection of sensor B connector, wiring harness and cylinder head area for damage or contamination
Backprobe sensor connector with key ON, engine OFF to measure signal voltage and reference voltage
Measure sensor B resistance at ambient and compare to OEM chart (or measure voltage while warming engine)
Check continuity of signal wire to ECM and check for short to battery or open to ECM

Reference voltage: typically 5.0 V or 3.3 V supply from ECM (verify with OEM manual)
Expected sensor output: generally varies between ~0.1 V and ~4.9 V across operating temperatures (depends on sensor type)
Open circuit or short to Vbatt often reads near reference or battery voltage (high)
Short to ground reads near 0 V (low)
Sensor is usually an NTC thermistor: resistance decreases as temperature increases — consult OEM resistance‑vs‑temperature chart for exact values

Connect a professional scan tool, confirm P2C3B and record freeze‑frame and live CHT sensor B data. Compare to CHT sensor A or coolant temp sensor if available.
Visually inspect sensor B, connector, and nearby harness for corrosion, damage, oil/coolant intrusion or rodent chew. Repair obvious damage.
With key ON (engine OFF) backprobe the sensor connector: verify reference voltage (≈5 V or 3.3 V) and ground presence. If no reference or ground, trace wiring to ECM.
Measure sensor signal voltage. If signal is near reference voltage (high), suspect open or short to battery. If near 0 V, suspect short to ground.
Disconnect sensor and measure sensor resistance at ambient; compare to OEM spec or verify it changes when heated (warm with hot water or heat gun carefully). Replace sensor if out of spec or not changing.
Check continuity and shorts: - continuity from sensor signal pin to ECM pin, - check for short to battery (≈12 V) or to ground, - measure resistance of ground circuit.
Repair wiring/connectors or replace sensor as indicated. After repairs, clear codes and perform a road/idle cycle while monitoring live data to confirm the fault does not return.
If wiring and sensor are good and fault persists, test or replace ECM/PCM only after ruling out all external faults.
Safety: take precautions when working near hot engine parts and use insulated tools when measuring live circuits.