Frayed, chafed, or intermittently shorted wiring in the crankcase pressure sensor circuit; Loose or corroded connector pins at the sensor or PCM; Failing crankcase pressure sensor with an internal intermittent fault; Clogged or restricted PCV system causing pressure fluctuations the sensor reports as erratic; Oil sludge or contamination on the sensor element causing unstable readings; PCM software or internal circuit issue (less common, but possible)

DTC codes / P05xx · Vehicle speed, idle control and auxiliary inputs / P051E

P051ECrankcase Pressure Sensor A Circuit Intermittent/Erratic

Q: What does code P051E mean?

Crankcase Pressure Sensor A Circuit Intermittent/Erratic. P051E means the powertrain control module (PCM) has detected an intermittent or erratic signal from the crankcase pressure sensor on circuit A. The PCM expects a steady, plausible voltage from this sensor, and it has seen the signal drop out, spike, or jump around outside normal limits for long enough to set the code.

P051E means the powertrain control module (PCM) has detected an intermittent or erratic signal from the crankcase pressure sensor on circuit A. The PCM expects a steady, plausible voltage from this sensor, and it has seen the signal drop out, spike, or jump around outside normal limits for long enough to set the code.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaVehicle speed, idle control and auxiliary inputs

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Rough idle or intermittent stalling when the crankcase pressure signal drops out
Oil leaks or excessive crankcase pressure if the sensor reading is skewed
Poor fuel economy or slightly rough running as the PCM adjusts fuel and airflow
A pending P051E that comes and goes with temperature or vibration
Unrelated driveability complaints if the erratic signal affects PCV or turbo control

Common causes, most likely first

Frayed, chafed, or intermittently shorted wiring in the crankcase pressure sensor circuit
Loose or corroded connector pins at the sensor or PCM
Failing crankcase pressure sensor with an internal intermittent fault
Clogged or restricted PCV system causing pressure fluctuations the sensor reports as erratic
Oil sludge or contamination on the sensor element causing unstable readings
PCM software or internal circuit issue (less common, but possible)

How to diagnose and fix it

Scan all modules and record freeze-frame data to see when the intermittent fault occurs
Inspect the crankcase pressure sensor connector and wiring for chafing, corrosion, or loose pins
Perform a wiggle test on the harness while watching live sensor voltage on a scan tool
Check the PCV system for clogs or restrictions that could cause pressure swings
Compare sensor voltage to a known-good value or use a gauge to verify actual crankcase pressure
Replace the crankcase pressure sensor if wiring and PCV checks pass but the signal remains erratic
Clear the code and road-test to confirm the repair, rechecking for pending codes

What a wiggle test reveals about P051E

A crankcase pressure sensor that reads erratically only when the engine is cold often points to a failing sensor element rather than wiring.
Many technicians replace the sensor first, but a chafed wire near the oil filter housing or exhaust heat shield is a frequent hidden cause.
A clogged PCV valve can create pressure pulses that the sensor reports as an erratic signal, setting P051E without any sensor fault.
This code can be set by a loose oil filler cap or dipstick that allows unmetered air and pressure changes, so check the simple things first.
Intermittent codes often leave no freeze-frame data, so a road test with a scan tool recording live data is more useful than static testing.

Can I keep driving with P051E?

You can usually drive with P051E, but avoid heavy acceleration or towing until it is diagnosed because an erratic crankcase pressure signal can affect PCV and turbo control. If the engine runs rough or stalls, stop driving and have it inspected promptly.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.