P01BC

Code

Generic P — Powertrain

Engine Oil Temperature Sensor B Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 31 EN: 68 RU: 39

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Page language: EN

Causes

Open or high-resistance wiring in EOT sensor B circuit
Poor or corroded connector terminals at the sensor or PCM
Short to battery voltage on the sensor signal or reference circuit
Failed EOT sensor (thermistor) with abnormal resistance
Poor ground or reference supply from PCM
Faulty PCM (rare) or internal circuit failure

Symptoms

Check Engine MIL illuminated and stored P01BC
Incorrect or no oil temperature reading on dash (if displayed)
Extended warm-up or altered engine management behavior
Possible reduced fuel economy or drivability issues during warm-up
No obvious oil leaks or mechanical oil temperature change

What to check

Scan for stored freeze-frame data and pending codes; note conditions when fault set
Visually inspect sensor connector and wiring for corrosion, damage, or moisture
Backprobe sensor connector to verify reference voltage and signal voltage with ignition ON
Measure sensor resistance at ambient and compare with spec (or remove sensor and check continuity)
Wiggle wiring while monitoring signal for intermittent faults
Check for related codes (PCM or other temperature sensors) that could indicate reference supply issues

Signal parameters

Typical reference voltage: 5 V (varies by manufacturer)
Expected sensor signal range: approximately 0.2–4.8 V depending on temperature and circuit design
Open-circuit/connector disconnected commonly yields signal near reference voltage (~5 V) -> 'circuit high'
NTC thermistor behavior: resistance decreases as oil temperature increases (verify against spec sheet)
Continuity to PCM signal pin should be low resistance (typically

Diagnostic algorithm

Retrieve freeze frame and related codes; record symptoms and conditions when the code set.
Perform a visual inspection of the EOT sensor B connector and harness for corrosion, loose pins, breaks, or damage. Repair as needed.
With ignition ON (engine OFF), backprobe sensor connector: verify PCM reference voltage present and measure signal voltage. If signal is high (near reference), suspect open or sensor failure.
Measure sensor resistance at the connector (or remove sensor). Compare resistance to manufacturer temperature/resistance table. If resistance is out of range, replace the sensor.
Check continuity between sensor signal pin and PCM input pin. Look for open circuit or high resistance; repair wiring if continuity is poor.
Inspect for short to battery voltage on the signal or reference circuit. If present, isolate and repair short.
After repairs or component replacement, clear codes, then perform functional test and road test to confirm code does not return.
If wiring and sensor test good but code persists, perform PCM input driver tests per manufacturer procedures or consider PCM replacement only after all other causes ruled out.

Likely causes

Disconnected or corroded connector at the oil temperature sensor
Damaged harness (chafing, rodent damage) causing an open or short
Failed oil temperature sensor B
Aftermarket wiring or recent service left connector loose
PCM reference or input driver fault (less common)

Fault status

⚠️ Status

P01BC — Engine Oil Temperature Sensor B Circuit High: PCM detects higher-than-expected voltage on the EOT sensor B input (possible open circuit or short to voltage).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2 hours