P051B

Crankcase Pressure Sensor A Circuit Range/Performance

Q: Is it safe to drive with P051B?

Usually yes — it's typically a sensor or ventilation reading fault. Still, have it checked, as it can flag a PCV problem that affects the engine over time.

Q: Can I just clear P051B?

You can, but it returns until the sensor, its wiring, or the ventilation issue is resolved.

Engine ventilation / crankcase Generic OBD-II High

What it means

P051B means the crankcase pressure sensor's signal is out of its expected range or doesn't match operating conditions. This sensor monitors pressure inside the crankcase, which ties into the PCV/engine ventilation system. It's usually a sensor, wiring, or ventilation-plumbing issue rather than a mechanical fault — the car typically drives normally, but it's worth checking since it can hint at a PCV problem.

High

Can I keep driving? Usually yes — the car generally drives normally; this is a crankcase-pressure monitoring fault, but don't ignore it, since it can point to a PCV/ventilation problem worth checking.

Real-world scan data

Seen in

166

scans in the past year

Found in

<0.1%

of scans

0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Usually little or no change in how the car drives
Possible related PCV/ventilation symptoms (whistle, oil residue) if a real pressure problem exists

Common causes

Most likely first

Faulty crankcase pressure sensorLikely
Wiring or connector fault in the sensor circuitCommon
Blocked, disconnected, or leaking PCV/crankcase ventilation hose skewing the readingCommon
Sensor port clogged with oil or sludgeLess often
Faulty ECM/PCM (rare)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data to see the reported crankcase pressure and conditions.
Inspect the crankcase pressure sensor connector and wiring for damage or corrosion.
Check the PCV system and crankcase ventilation hoses for blockage, leaks, or disconnection.
Verify the sensor port isn't plugged with oil/sludge; clean if needed.
If the plumbing and circuit are good, replace the crankcase pressure sensor. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P051B?+

Usually yes — it's typically a sensor or ventilation reading fault. Still, have it checked, as it can flag a PCV problem that affects the engine over time.

Can I just clear P051B?+

You can, but it returns until the sensor, its wiring, or the ventilation issue is resolved.

Read & clear P051B yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX