Technical Description of OBD-II Trouble Code
Circuit for Crankcase Pressure Sensor
What does that signify?
This is a generic diagnostic trouble code (DTC) for the powertrain and is commonly found in OBD-II vehicles. It can be applicable to various vehicle makes such as Ford, Dodge, Ram, Jeep, Fiat, Nissan, etc.
Among the numerous sensors that the ECM (Engine Control Module) needs to monitor and adjust in order to maintain the proper functioning of your engine, the crankcase pressure sensor is responsible for providing the ECM with accurate crankcase pressure values. This is crucial for maintaining a healthy atmosphere within the engine.
Since the engine generates a significant amount of fumes internally, especially while running, it is essential for the ECM to have precise crankcase pressure values. This is necessary not only to prevent excessive pressure that could damage seals and gaskets, but also to recycle these burnable fumes back into the engine through the PCV (Positive Crankcase Ventilation) system.
Any unused burnable crankcase fumes are directed into the engine’s intake to be burned, thereby improving emissions and fuel economy. Therefore, it is important to address any issues related to this fault promptly. Neglecting this fault may lead to gasket failure, o-ring leaks, shaft seal leaks, and other problems. As the name suggests, the sensor is usually mounted on the crankcase.
Code P051A Crankcase Pressure Sensor Circuit and related codes are activated by the ECM when it detects that one or more electrical values in the crankcase pressure sensor circuit are operating outside the desired range.
When your instrument cluster displays the P051A Crankcase Pressure Sensor Circuit code, it means that the ECM has detected a general fault in the crankcase pressure sensor circuit.
Here is an example of a crankcase pressure sensor (specifically for a Cummins engine):
What is the severity of this DTC?
In the grand scheme of things, this fault can be considered moderate-low. While immediate drastic further damage is not likely, it is important to address this issue sooner rather than later. As mentioned earlier, neglecting this fault can lead to various potential issues, so it is crucial to keep them in mind.
What are some of the symptoms of the code?
The symptoms of a P051A diagnostic code may include:
What are some of the common causes of the code?
The causes of this P051A engine code may include:
What are some diagnostic and troubleshooting steps for P051A?
The first step in the troubleshooting process for any malfunction is to refer to the Technical Service Bulletins (TSB) for known issues with the specific vehicle.
For example, there are known issues with some Ford EcoBoost vehicles and some Dodge/Ram vehicles that have TSBs related to this DTC and/or related codes.
Advanced diagnostic steps are highly specific to the vehicle and may require specialized equipment and knowledge to be performed accurately. The basic steps provided below should be followed, but it is recommended to consult a vehicle year/make/model/powertrain specific repair guide for detailed steps.
Basic Step #1
Firstly, for this fault, it is advisable to open the oil cap on the top of the engine (location may vary) and inspect for any visible signs of sludge build-up. Sludge can be caused by factors such as infrequent oil changes or longer than recommended intervals between oil changes. Personally, I recommend changing conventional oil every 5,000 kilometers and synthetic oil every 8,000 to 10,000 kilometers. However, these intervals may vary depending on the manufacturer’s recommendations. It is always better to err on the side of caution. A PCV (Positive Crankcase Ventilation) issue can also cause moisture to enter the system and result in sludge formation. Regardless, ensure that your oil is clean and at the appropriate level.
NOTE: Avoid overfilling the engine with oil. If this happens, do not start the engine and drain the excess oil to bring the level within the acceptable range.
Basic Step #2
Test the sensor by following the manufacturer’s specific desired values as stated in your service manual. This usually involves using a multimeter to test different values between pins. Record and compare the findings with the specifications for your make and model. If the values fall outside the specified range, the crankcase pressure sensor should be replaced.
Basic Step #3
Since crankcase pressure sensors are typically mounted directly on the engine block (also known as the crankcase), the harnesses and wires involved are routed through crevices and areas with extreme temperatures (such as the exhaust manifold). When visually inspecting the sensor and circuits, be aware of this fact. The wires and harnesses are exposed to the elements, so check for any hardened or cracked wires or moisture in the harness.
NOTE: Ensure that the connector is securely connected and free of any oil residue.
