Fix P051B: Crankcase Pressure Sensor Circuit Range

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Fix P051B
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Typically, this is a common powerful, diagnostics trouble code (DTC) that is happening to cars equipped with the OBD-II diagnostic system. It’s most often seen in the car companies like Ford, Dodge, Ram, Jeep, Fiat company, Nissan, and other comparable car producers, while it may be found in a variety of different sizes and model types as well. 

Here comes the explanation of what a P051 DTC of the information signifies in practical terms.

P051B Meaning:

P051B Meaning: P051B Crankcase Pressure Sensor Machine Circuit Efficiency/Performance.

OBD-II Code P051B: Symptoms, Causes & Diagnose


  • Fuel efficiency has been reduced.
  • The gasket is leaking.
  • The check engine light is illuminated.
  • Internal crankcase pressure measurements are incorrect.
  • Problems with the engine’s performance.
  • Black soot is spewed from the engine.
  • A buildup of sludge.


  • Defective crankcase pressure sensor.
  • There are electrical problems.
  • PCV valve that is not working correctly.
  • Other issues include a clogged PCV system and other issues such as broken runners or tubes.
  • Lines that have been disconnected or chafed.

How to Diagnose?

P051B is a general diagnostic trouble code that applies to automobiles with onboard diagnostics (OBD Obd2 Scanner ). However, depending on the vehicle’s year, make, and model, the methods for diagnosing this code and the actions required for repair may differ.

A certified technician should be brought in to diagnose your car if you are not acquainted with the procedure of diagnosing problem codes at this time. 

For those who have experienced do-it-yourselfers who know their way around performing diagnostic tests on their vehicles, they may choose to take the plunge and do the task themselves.

Tools You Need: A multimeter, a value checker, an OBD2 connection device, and other items are necessary to resolve the p051b error code.


Advanced diagnostic procedures become more vehicle-specific, and they may need specialized equipment and expertise to be performed correctly. 

We’ve included the basics here, but you should consult a vehicle year, make, model, and powertrain-specific repair guide for more information on particular instructions for your vehicle.

Step 1: The most fundamental step: First and foremost, while dealing with this issue, I would remove the oil cover from the top of the engine (the location of which varies) and visually check the engine for any evident evidence of sludge build-up. 

Sludge may be created by anything as simple as a lack of oil changes or by following suggested intervals for a more extended period. I don’t drive conventional oil for more than 5,000 kilometers on a single tank of gas. For instance, I go around 8,000 to 10,000 kilometers, maybe more. 

This varies from maker to manufacturer; nevertheless, in my professional experience, I’ve seen manufacturers specify more significant intervals than the usually advised intervals for various reasons. I like to be on the safe side and recommend you to do the same. 

A problem with PCV (Positive Crankcase Ventilation) might allow moisture to enter the system, resulting in sludge formation. In any case, check to see that your oil is clean and complete. 

IMPORTANT: Be careful not to overfill the engine with oil. If this occurs, do not start the engine; instead, drain the oil until the level is within acceptable limits.

Step 2: The Fundamentals: Test the sensor using the manufacturer’s intended values from your service manual to run it through its paces. This will require utilizing your multimeter and experimenting with different values between pins. If there is any deviation from specifications, the crankcase pressure sensor should be replaced.

Step 3: The fundamentals: Because crankcase pressure sensors are often installed directly to the engine block (also known as the crankcase), the harnesses and wires involved are routed around cracks and around high-temperature locations to ensure proper operation (i.e., exhaust manifold). When visually evaluating the sensor and circuitry, keep this in mind as well. 

Because these wires and harnesses are exposed to the weather, they should be checked for hardened/cracked wires and moisture in the saddle before being used.

When diagnosing p051b, there is a frequent error that you must avoid

Occasionally, vehicle repair providers may forgo the TSB-recommended diagnostic and replace the sensor with a different one.

However, not only does this not guarantee that this will resolve the problem, but it also increases the danger of causing a more significant and costly problem in the future if your vehicle’s gasket or crankcase seal fails as a result of excessive or insufficient pressure.

How to fix p051b Obd2 Code?

How to fix p051b?

Are you looking for a means to repair this error code? If this is the case, you have arrived at the proper location. To ensure that you get the best possible assistance, please review the procedures listed below:

  • Correct the problem with the internal electrical problem that exists inside the sensor.
  • If the engine control module is not operating correctly, it should be replaced.
  • Restore the positive crankcase ventilation valve to its original position.
  • If there are any difficulties with the crankcase pressure sensor, it is necessary to replace the sensor.
  • Check to see that the clogged PCV system has been adequately repaired.
  • If the crankcase pressure sensor has been opened or shorted, it is always possible to replace it.
  • Correct the issue of water ingress as thoroughly as possible.

Examine the crankcase pressure sensor for damage.

  • Tips for further avoiding p051b obd2 error:
  • Make sure that the blocked PCV system is correctly fixed.
  • If the crankcase pressure sensor has been opened or shorted, it is always possible to replace it.
  • Correct the issue of water ingress as thoroughly as possible.
  • Examine the crankcase pressure sensor for damage.

It is not necessary to worry if you get a P051B DTC; nonetheless, you should take your vehicle to an authorized automotive repair shop as soon as you can.

The most likely explanation is that you’re merely past due for an oil change or that the sensor and wire harness have failed.

If it turns out to be more difficult, at the very least, you will have identified and resolved the problem before it caused significant and costly engine damage.