P052E Positive pressure crankcase ventilation regulator valve performance

OBD-II DTC Datasheet

Positive characteristic of the crankcase ventilation regulator valve

What does this mean?

This Generic Powertrain Diagnostic Trouble Code (DTC) is commonly applied to many OBD-II vehicles. This may include, but is not limited to, Ford, Dodge, Ram, Volvo, etc.

If you have a P052E code stored in your OBD-II vehicle, it means that the powertrain control module (PCM) has detected a signal from the crankcase pressure sensor that indicates the presence of an inappropriate degree of pressure.

The crankcase air density (pressure) is monitored by the PCM using the input voltage signal from the crankcase pressure sensor. The crankcase pressure sensor input voltage is assumed (PCM) as actual pressure units. Either kilopascals (kPa) or inches of mercury (Hg) are used to measure crankcase pressure. The crankcase pressure sensor is usually located in or near one of the valve covers.

Since the bottom end of the internal combustion engine must be sealed to prevent oil leakage, a certain pressure builds up there. This pressure arises from sudden changes in temperature, engine oil vapors and rapid centrifugal movement of the crankshaft, connecting rods, etc.

The positive crankcase ventilation (PCV) system uses a carefully controlled intake vacuum to relieve pressure from the crankcase through a specially designed valve (PCV valve) that allows only one direction of flow. In the vast majority of automotive applications, the PCV valve uses direct vacuum from the intake manifold. In this particular case, the PCV vacuum is controlled by an electronically controlled PCV control valve. The PCM uses the input from the crankcase pressure sensor to determine how much vacuum pressure needs to be applied to the PCV for optimal performance. A constant battery voltage source is usually supplied to one terminal of the PCV control valve, and the PCM provides ground as needed to close the circuit, install the control valve into its housing, and achieve the desired degree of PCV vacuum.

If the PCM detects that the desired crankcase pressure level cannot be achieved by the PCV regulator valve, a P052E code will be stored and a malfunction indicator lamp (MIL) may illuminate.

Photo of a PCV valve, one of the system components:

What is the severity of this DTC?

Improper crankcase pressure can cause engine oil to leak. The P052E code should be classified as serious and treated accordingly.

What are some of the symptoms of the code?

Symptoms of a P052E engine code may include:

Engine oil leaks
Smoke (steam) from the engine compartment
Hissing (suction) from the engine compartment
Driving problems caused by vacuum leak

What are some of the common causes for the code?

Reasons for this code may include:

Bad PCV Control Valve
Faulty PCV valve
Defective crankcase pressure sensor
Open or short circuit in PCV control valve / crankcase pressure sensor wiring
Faulty PCM or PCM programming error

Example of a crankcase pressure sensor: P052E Positive pressure crankcase ventilation regulator valve performance

What are some of the P052E troubleshooting steps?

In my experience, diagnosing a P052E code will require a hand held vacuum gauge, a diagnostic scanner, a digital volt / ohm meter (DVOM), and a reliable source of vehicle information.

A manual vacuum pressure test must be performed before diagnosing any crankcase / PCV underpressure codes. If the engine does not generate sufficient vacuum, it must be repaired before proceeding with diagnostics. To perform a manual vacuum pressure test, disconnect the PCV vacuum hose and connect a pressure gauge to it. Your vehicle resource should include specifications for minimum engine vacuum.

Check all PCV hoses for cracks or breakage and repair if necessary. Cracked or broken PCV vacuum hoses can contribute to the conditions that led to the storage of the P052E.

If the engine is in good working order and there are no vacuum leaks, continue to visually inspect all wiring and connectors on the PCV control valve and crankcase pressure sensor. Make repairs as needed. Then I connected the scanner to the car diagnostic port and got all stored codes and freeze frame data. Recording this information can help you as your diagnosis progresses. Then clear the codes and test drive the vehicle to make sure the code is cleared.

Use your Vehicle Information Resource for connector views, wiring diagrams, connector pinouts, component testing procedures, and specifications. All this information will be required to continue diagnostics.

Checking PCV Regulator Valve and Circuits (KOEO)

Use the scanner to manually activate the PCV control valve.
Test the supply circuit to the PCV regulator valve with the positive test lead from the DVOM.
Use the negative test lead to test the PCV regulator valve ground.
If there is battery voltage at the PCV control valve connector, suspect the valve is defective.
You can check the valve with DVOM.
If it doesn't meet the recommended specs, it's definitely useless.
If there is no voltage at the PCV pressure regulator valve connector, continue to the next step.

Check the PCV regulator valve voltage output circuit at the PCM connector.

Use the positive test lead from the DVOM to test the output voltage of the PCV regulator valve at the PCM connector.
The negative test lead must be connected to a known good ground.
If there is an output voltage signal on the PCM connector that is not on the regulator valve connector, you have an open circuit between the two.
If there is no PCV regulator valve output on the PCM connector, go to the next step.

Check crankshaft pressure sensor with DVOM

Key on and engine off (KOEO) set the DVOM to resistance setting and follow manufacturer's procedures / specifications to test the crankcase pressure sensor with disconnected connector.
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 check the reference voltage (typically 5 volts) and ground at the crankcase pressure sensor connector.

With the KOEO transducer and crankcase pressure transducer disconnected, check the reference voltage contact at the transducer connector with the positive test lead from the DVOM.
Connect the negative test lead to the grounding terminal of the connector to test the entire circuit.
If no voltage reference is found at the sensor connector, locate the PCM and check the corresponding circuit at the PCM connector. Use the positive test lead DVOM.
The negative test lead must be connected to a known good ground for this test.
If there is no voltage reference on the PCM connector, suspect that the PCM is faulty or a programming error.
If there is no ground at the sensor connector, use your vehicle information source to find a ground source and make sure it is securely attached to the engine block or battery.
If there is a voltage and ground reference at the crankcase pressure sensor connector, go to the next step.

Check the voltage of the crankcase pressure sensor signal circuit using the DVOM.

With the key on a running engine (KOER) and a reconnected crankcase pressure sensor, use the positive DVOM lead to test the sensor signal voltage just behind the connector.
The negative test lead must be re-connected to the battery ground.
Use a vacuum gauge to get the correct crankcase pressure and compare the sensor signal voltage to the pressure versus voltage diagram on your vehicle's information resource.
If the signal voltage of the crankcase pressure sensor is incorrect, consider the sensor as faulty.
If the crankcase pressure sensor signal voltage (at the sensor connector) is showing the correct voltage, go to the next step

Check the signal circuit of the crankcase pressure sensor at the PCM connector.

With KOER, use the positive test lead from the DVOM to test the signal circuit of the crankcase pressure sensor at the PCM connector.
The negative test lead must be connected to the battery ground.
If the correct crankcase pressure sensor signal is found on the sensor connector but not on the corresponding PCM connector circuit, suspect there is an open circuit between the two.

If the PCV regulator valve / crankcase pressure sensor and all circuits are within specifications, suspect a PCM failure or PCM programming error.

Technical Service Bulletins (TSBs) that match the vehicle in question (as well as stored symptoms and codes) can help diagnose.

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