Error Code P051F is defined as Positive Crankcase Ventilation Filter Restriction. This is a generic trouble code, meaning it applies to all cars equipped with OBD-II system, particularly those made since 1996 up to present. It is particularly common among Dodge, Ford, Ram, and Volvo, though it can appear in almost all makes and models.
When Error Code P051F is stored, that means the PCM (powertrain control module, also known as ECM or engine control module in other 2009 Saturn Vue makes) has detected a signal from the CKP sensor (crankcase pressure sensor) that indicates an overpressure condition. This sensor is usually located in or near one of the valve covers.
The pressure or air density in the engine’s crankcase is monitored by the PCM through an input voltage signal which comes from the CKP sensor. These input voltages are received as actual units of pressure, which can be either kilopascal (kPa) units or inches of mercury (Hg) unit of measurement.
To prevent oil leaks, the lower end of the internal combustion engine must be sealed, and this creates a certain amount of pressure. This pressure is caused by drastic changes in the temperature, while vapors created by the engine oil, and the rapid centrifugal motion of the crankshaft, connecting rods, etc.
The PCV (positive crankcase ventilation) system uses carefully controlled intake vacuum, through a specially designed PCV valve which only allows a single direction of flow, to draw pressure from the crankcase. For most cars, the PCV valve itself is responsible for filtering unwanted oil and debris and keep it from getting into the intake manifold. For this application in particular, the PCV filter was added for precautionary measures to protect the engine air delivery system from excessive oil and debris.
The PCM monitors the pressure level in the CKP sensor. If it exceeds the parameters, then the Error Code P051F will be stored.
As with other error codes, this code activates the Check Engine light and registers the code to your 2009 Saturn Vue ’s memory system. Other common symptoms include:
Tools needed to diagnose this code include a manual vacuum pressure gauge, digital volt/ohmmeter (DVOM), a diagnostic scanner, and a reliable source of 2009 Saturn Vue information.
Manual vacuum pressure test must be performed before diagnosing any excessive CKP or PCV related codes. If the engine is unable to produce enough of a vacuum, then it must be fixed before moving on with further diagnosis. To do a manual vacuum test, the PCV vacuum must be disconnected, then attach the vacuum pressure gauge on its spot. You can get the information about your minimum engine vacuum from your 2009 Saturn Vue information.
Then, check all PCV hoses for any signs of damages and do the necessary repairs. Cracked or collapsed PCV vacuum hoses can contribute to this problem. If there is enough vacuum on the inlet side of the PCV filter, but not enough on the outlet side, then that means the filter is clogged.
If the engine is in good condition and there are no vacuum leaks, then continue with the visual inspection of the CKP sensor, connectors, and wirings. Repair as needed.
Then, retrieve all the codes stored in your 2009 Saturn Vue ’s memory system and their freeze frame data by connecting the scanner to your 2009 Saturn Vue ’s diagnostic port. Take note of the information, then clear the codes and take your 2009 Saturn Vue for a test drive to see if the code comes back.
Get the right face views, connector pin-out charts, wiring diagrams, component testing procedures, and specs from your 2009 Saturn Vue information source. You will need this information to proceed with your diagnosis.
Use the DVOM to test the CKP pressure sensor
Use the DVOM to test the reference voltage (5V) and ground at the CKP sensor connector using
Use DVOM to rest CKP sensor signal circuit voltage
Test the crankcase pressure sensor signal circuit through the PCM connector
Depending on the diagnosis, common repairs for this code include:
Since Error Code P051F results from an engine oil break, then this code is considered severe and must be addressed as soon as possible.