What does it mean?
This generic powertrain diagnostic trouble code (DTC) generally applies to many OBD-II vehicles. This may include, but is not limited to, vehicles from Ford, Dodge, Ram, Volvo, etc.
If a P052E code is stored in your OBD-II vehicle, it means that the Powertrain Control Module (PCM) has detected a signal from the crankcase pressure sensor indicating that an inappropriate pressure level exists.
The density (pressure) of the air in the engine crankcase is monitored by the PCM using a voltage input signal from the crankcase pressure sensor. The crankcase pressure sensor input voltage is received (by the PCM) as actual pressure units. Kilopascal (kPa) units or inches of mercury (Hg) are used to measure crankcase pressure. The crankcase pressure sensor is typically located in or near one of the valve covers.
Because the lower end of the internal combustion engine must be sealed to prevent oil leaks, a certain amount of pressure is created there. This pressure is caused by drastic temperature changes, vapors created by the engine oil, and the rapid centrifugal movement of the crankshaft, connecting rods, etc.
The Positive Crankcase Ventilation (PCV) system uses a carefully controlled intake vacuum to draw pressure from the crankcase through a specially designed valve (PCV valve) that only allows one direction of flow. In the vast majority of vehicle applications, the PCV valve uses direct vacuum from the intake manifold. In this particular application, the PCV vacuum is regulated using an electronically controlled PCV regulation valve. The PCM uses an input signal from the crankcase pressure sensor to determine the vacuum pressure to apply to the PCV for optimal performance. A constant supply of battery voltage is typically applied to one terminal of the PCV regulation valve, and the PCM provides a ground as needed to complete the circuit, position the regulation valve in its housing, and achieve the desired PCV vacuum level.
If the PCM detects that the desired level of crankcase pressure cannot be achieved with the PCV regulation valve, a P052E code will be stored and a Malfunction Indicator Lamp (MIL) may be illuminated.
Photo of a PCV valve, a component of the system:
How severe is this DTC?
Incorrect crankcase pressure can lead to engine oil leaks. A P052E code should be classified as severe and treated accordingly.
What are some of the symptoms of the code?
Symptoms of a P052E engine code may include:
Engine oil leaks
Smoke (vapor) from the area under the hood
Hissing (suction) noise from the engine area
Driving issues caused by a vacuum leak
What are some of the common causes of the code?
Causes
of this code may include:
Faulty PCV regulation valve
Defective PCV valve
Faulty crankcase pressure sensor
Open or shorted wiring of the PCV regulation valve / crankcase pressure sensor
PCM malfunction or PCM programming error
Example of a crankcase pressure sensor:
What are the troubleshooting steps for P052E?
Based on my experience, a manual vacuum gauge, a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information will be needed when diagnosing a P052E code.
A manual vacuum pressure test should be performed before diagnosing any insufficient crankcase pressure / PCV related codes. If the engine fails to produce sufficient vacuum, it must be repaired before proceeding with your diagnosis. To perform a manual vacuum pressure test, disconnect the PCV vacuum hose and attach your vacuum gauge to it. Your vehicle information resource should provide specifications regarding minimum engine vacuum.
Check all PCV hoses for signs of cracking or breakage and perform necessary repairs. Cracked or collapsed PCV suction hoses can contribute to the conditions that caused the P052E to be stored.
If the engine is in good operating condition and there is no vacuum leak, continue with a visual inspection of all wiring and connectors for the PCV regulation valve and the crankcase pressure sensor. Perform necessary repairs.
Next, I would connect the scanner to the vehicle’s diagnostic port and retrieve all stored codes and freeze frame data. Writing down this information can help you as your diagnosis progresses. After that, clear the codes and test drive the vehicle to see if the code resets.
Use your vehicle information resource to obtain connector face views, wiring diagrams, connector pinout charts, component testing procedures, and specifications. All of this information will be needed to proceed with your diagnosis.
Testing the PCV Regulation Valve and Circuits (KOEO)
Use the scanner to manually activate the PCV regulation valve
Probe the PCV regulation valve power supply circuit with the DVOM’s positive test lead
Use the negative test lead to test the ground of the PCV regulation valve
If there is battery voltage at the PCV regulation valve connector, suspect the valve is faulty
You can test the valve using the DVOM
If it does not meet the recommended specifications, it is certainly not good
If there is no voltage at the PCV regulation valve connector, proceed to the next step
Testing a PCV Regulation Valve Voltage Output Circuit at the PCM Connector
Use the DVOM’s positive test lead to probe the PCV regulation valve output voltage at the PCM connector
The negative test lead should be connected to a known good ground
If there is an output voltage signal at the PCM connector, which is not present at the regulation valve connector, you have an open circuit between the two
If no PCV regulation valve output signal is present at the PCM connector, proceed to the next step
Test the crankcase pressure sensor using the DVOM
With the key on and engine off (KOEO), set the DVOM to the ohms setting and follow the manufacturer’s procedures/specifications for testing the engine crankcase pressure sensor with the connector unplugged
If the sensor in question does not meet the manufacturer’s specifications, it should be considered defective
If the sensor meets the manufacturer’s specifications, proceed to the next step
Use the DVOM to test the reference voltage (usually 5 volts) and a ground at the crankcase pressure sensor connector
With KOEO and the crankcase pressure sensor disconnected, probe the sensor connector’s reference voltage pin with the DVOM’s positive test lead
Connect the negative test lead to the connector’s ground pin to test the entire circuit
If no reference voltage is detected at the sensor connector, locate the PCM and test the corresponding circuit at the PCM connector. Use the DVOM’s positive test lead
The negative test lead should be connected to a known good ground for this test
If there is no reference voltage at the PCM connector, suspect a PCM failure or programming error
If there is no ground at the sensor connector, use your vehicle information source to locate the ground source and ensure it is securely attached to the engine block or battery
If there is reference voltage and ground at the crankcase pressure sensor connector, proceed to the next step
Test the crankcase pressure sensor signal circuit voltage using the DVOM
With the key on engine running (KOER) and the engine crankcase pressure sensor reconnected, use the DVOM’s positive lead to probe the sensor’s signal voltage just behind the connector
The negative test lead should again be connected to a battery ground
Use the vacuum gauge to obtain the correct crankcase pressure and compare the sensor’s signal voltage to the pressure-voltage chart in your vehicle information resource
If the crankcase pressure sensor signal voltage is incorrect, consider the sensor faulty
If the crankcase pressure sensor signal voltage (at the sensor connector) reflects the correct voltage level, proceed to the next step
Test the crankcase pressure sensor signal circuit at the PCM connector
With KOER, use the DVOM positive test lead to probe the crankcase pressure sensor signal circuit at the PCM connector
The negative test lead should be connected to a battery ground
If a correct crankcase pressure sensor signal is found at the sensor connector but not at the corresponding circuit of the PCM connector, suspect an open circuit between the two
If the PCV regulation valve / crankcase pressure sensor and all circuits meet specifications, suspect a PCM failure or PCM programming error.
Technical Service Bulletins (TSBs) that parallel the vehicle in question (as well as the symptoms and stored codes) can assist in your diagnosis