What it means
The ECM detects a circuit intermittent/erratic fault on the crankcase pressure sensor b circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Crankcase pressure sensor B reports crankcase pressure to the ECM for engine and ventilation control. This intermittent/erratic code sets when the signal from sensor B changes unpredictably or drops in and out, often as a connector or ground loses contact with vibration.
Common causes
Most likely first.
- Sensor connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
Symptoms
- Check-engine light
- Rough or uneven idle
- Intermittent changes in engine performance
How to diagnose it
- Check freeze-frame data and code status, then watch sensor B live data for dropouts while the engine idles.
- Inspect sensor B's connector for incomplete latching, loose pins, corrosion, or oil contamination and check the harness for strain or chafing.
- With the engine running and using safe access, gently move the sensor B harness while monitoring the signal for sudden changes.
- Check sensor B's ground reference, power, and signal wiring for intermittent opens or high resistance using the manufacturer's procedure.
- Repair the unstable connection or replace a sensor that fails its test, then repeat the live-data check and confirm the code does not return.
Common fixes
- Fully seat and secure the crankcase pressure sensor B connector.
- Clean corroded connector contacts and repair loose or damaged pins.
- Repair chafed or internally broken sensor B wiring and restore a sound ground.
- Replace sensor B if its output remains erratic with stable wiring and connections.
Can I keep driving?
Driving may be reasonable if the engine remains predictable, but stop if performance suddenly deteriorates or the engine begins to run roughly. The intermittent signal can cause inconsistent engine control, so avoid long trips until the connection is repaired.
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.