P051B – Crankcase Pressure Sensor Circuit Range/Performance

Akindayini Temiloluwa

By Akindayini Temiloluwa (Contact Me)
Last Updated 2022-04-15
Automotive mechanic

CodeFault LocationProbable Cause
P051B Crankcase Pressure Sensor Circuit Range/Performance
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PCM malfunction, faulty Pcv valves, electrical issues

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What Does Code P051B Mean?

NOTE: P051B is common on 2015 and newer Ford vehicles with EcoBoost engines (1.5L, 2.7L, 3.5L).  Vehicles affected include Ford Escape, EcoSport, F-150, Fusion, Ranger, etc.  This code may be due to the crankcase pressure sensor/tube assembly. To correct the condition, check TSBs and follow the Service Procedure steps to replace the crankcase pressure sensor/tube assembly.

The Diagnostic Trouble Code (DTC) P051B is a trouble code that means Crankcase Pressure Sensor Circuit Range/Performance. It has to do with monitoring the pressure level that is gathering up in the engine. The crankcase pressure sensor does not just monitor pressure but also the engine oil present in the crankcase. The DTC works using a pressure sensor that correctly measures and determines the pressure building level in the crankcase. This is to prevent the gaskets and other seals from getting damaged.

To understand how important the Crankcase Pressure Sensor is, we will briefly explain the crankcase. The Crankcase is the largest part of the engine. It houses the important parts of the engine like the connecting rods, pistons, and cylinders. Any damage to any part of this part of the engine could be fatal to the totality of the engine; this is why this part of the engine must be monitored properly.

The Crankcase Pressure Sensor is created to ensure that the engine works under a suitable internal condition. During normal working conditions, the engine produces a lot of gas that continuously builds up within the engine. These gases are normal during the engine’s operation but could also be dangerous if not monitored properly. Excessive gas or pressure in the engine’s crankshaft can cause the engine to have oil leaks and can cause leaks in other engine seals, including the gasket.

The Crank Pressure Sensor monitors these gases in the engine’s crankshaft. It works with the Engine Control Module (ECM), popularly considered the “brain.” The ECM performs the function of monitoring the engine’s performance and making sure that it functions perfectly. All modern vehicles come with an ECM system. All the car’s engine sensors are connected to the ECM system, ensuring that all the vehicle parts are working at optimal capacity. ECM helps regulate major engine parts, including a mixture of air and fuel and an emission system.

The Crank Pressure Sensor works with the ECM system by sending valuable data about the condition of pressure in the crankshaft to the ECM. The ECM then ensures that the gases do not reach a harmful extent. It does this by redistributing the gases into the engine for use. The ECM can achieve this with the help of a Positive Crankshaft Ventilation (PVC) system.

The P051B Code can get activated when the data from the Crank Pressure Sensor shows that the pressure built up in the crankshaft is above the normally required pressure. The sensors in the crankshaft pick up the problem. The sensors then send the data to the ECM, which triggers the Positive Ventilation (PVC) system to correct the problem. If the problem can not be regulated due to issues within the engine system or external factors, then the P051B is triggered. The code is shown on the OBD system, telling you that there is a problem with the engine pressure level.

Where is the P051B sensor located?

The P051B is also known as the Crankcase Pressure Sensor Circuit Range/Performance. The crankcase pressure sensor can be found in the crankcase within the engine. It is placed in a strategic position where it can easily monitor the pressure in the engine system. It is also placed in a position where it will not be damaged by the heat generated by the engine system.

What are the common causes of code P051B?

The code P051B can be caused by several issues that may be going on in the engine system or crankcase. The code must be taken seriously when noticed to prevent further damage to the engine system. They include:

  • Faulty crankcase pressure sensor
  • Defective Electrical connection
  • PCM malfunction
  • Faulty PCV valve
  • Obstructed PCV system

There are also other problems in the engine system that can cause code P051B to come up. Also, another popular cause that can trigger the code may be a malfunction or glitch in the system.

You should note that diagnosing non-professionals should be very careful in attempting to repair this problem. This is because the P015B is an engine-related issue, and as we know, the engine is a very complicated part of the vehicle. Unlike other parts of the car, mistakes made in the engine could cause serious damage that could cause a fortune to fix.  Also, many wrong diagnostics due to the complication of the vehicle’s electronic components could cause serious problems to the vehicle’s electrical system.

What are the symptoms of code P051B?

Like other diagnostic codes, the P015B comes with some symptoms that, when your vehicle begins to show them, could be due to the P051B code. Here are some of the symptoms of the P051B code:

  • Leaks in the gasket
  • Smokes from the engine
  • Reduced engine performance
  • Triggered engine light
  • Bad fuel mileage

Codes Related to P051B

Other codes may come up due to the P015B. These codes include issues that have to do with problems related to the crankcase. Some of the code that may come up with the P015B includes

  • P04DB Code – This code has to do with a disconnected crankcase ventilation system. The crankcase ventilation system is an important part of the engine system that helps remove excess gas from the crankcase and also reduces pressure in the engine system.

  • P052E Code – As we know, the Positive Crankshaft Ventilation (PVC) system is an important instrument in controlling the pressure in the crankcase. Once this PVC is damaged or lets off the wrong signal due to failed operating signals, the P052E code will come up.