What it means
Engine oil temp sensor B signal voltage below expected range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Engine oil temperature sensor B sends an electrical signal representing oil temperature to the control module. This circuit-low code means the module sees sensor B's signal below its expected electrical range, commonly because the signal is being pulled toward ground or a connection has excessive resistance.
Common causes
Most likely first.
- Signal wire shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check-engine light on
- Oil temperature reading may be inaccurate or unavailable
How to diagnose it
- Use the scan tool to record freeze-frame data and check whether sensor B's oil-temperature reading is implausibly cold or unavailable while the code is present.
- Inspect sensor B's connector and harness for moisture, corrosion, rubbed-through insulation, pin damage, or a signal wire touching ground.
- Check the connector terminals for corrosion and pin fit, including whether any terminal is pushed back and fails to contact the sensor.
- Monitor the live reading while gently moving the sensor B harness and connector to identify a short or poor connection that changes with movement.
- Measure sensor B's signal circuit for a short to ground and test its power and ground connections against the wiring diagram and manufacturer's specification.
Common fixes
- Clean and dry the sensor B connector and restore a secure terminal connection.
- Repair chafed insulation or a signal wire shorted to ground.
- Replace corroded or loose sensor B connector terminals and renew damaged seals.
- Replace sensor B if its signal remains below range after the wiring and connections pass their checks.
Can I keep driving?
If there are no oil-pressure warnings and the engine behaves normally, drive only as needed and keep trips short because the oil-temperature reading may be unreliable. Stop if an oil-pressure warning or signs of overheating appear.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.