P051E: Crankcase Pressure Sensor Circuit Intermittent or Erratic

What it means

Same as P051A with intermittent or erratic signal. 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

Crankcase pressure sensor A provides a changing signal that the control module uses to monitor crankcase pressure and PCV operation. P051E sets when that signal becomes intermittent or erratic instead of changing consistently with engine conditions. A vibration-sensitive connector contact or harness rubbing against a vibrating part can cause the signal to drop in and out.

Common causes

Most likely first.

1. Intermittent contact at connector
2. Connector with intermittent contact under vibration
3. Harness routed against vibrating component

Symptoms

• Check-engine light on
• Rough or unstable idle that may come and go
• Whistling or hissing from the engine area
• Possible oil leaks or increased oil consumption

How to diagnose it

1. Review freeze-frame data and monitor sensor A’s live signal for sudden jumps or dropouts as the engine runs.
2. Inspect the sensor A connector for loose terminals, corrosion, water, or signs that the connector can move under vibration.
3. Check the harness routing for rubbing, tension, or contact with a vibrating engine component.
4. Gently move the connector and harness while watching the scan-tool signal to locate an intermittent change.
5. If the fault persists, test the sensor circuit for intermittent opens or shorts and compare its response with the manufacturer’s specification.

Common fixes

• Reseat and secure a loose sensor A connector.
• Repair connector terminals that lose contact under movement or vibration.
• Reroute and secure the harness away from rubbing or vibrating parts.
• Repair an intermittent open or short in the wiring.
• Replace crankcase pressure sensor A if its output remains erratic with a sound, stable connection.

Can I keep driving?

Driving may be possible if the engine is running normally, but avoid long trips until the intermittent signal is found because the fault can return unexpectedly and cause unstable idle. Stop if the engine begins running very roughly or an oil leak appears.