Fix P052E: Mechanic’s solutions that WORKED

The code P052E: “Positive Crankcase Ventilation Regulator Valve Performance” signals an issue with the engine’s Positive Crankcase Ventilation (PCV) system, specifically related to the regulator valve’s performance. It typically arises from a defective valve or blockages within the breather system and could result in inefficient engine operation if left unaddressed.

P052E quick overview

Meaning	P052E: “Positive Crankcase Ventilation Regulator Valve Performance.”
Is it serious?	The seriousness can range; it often does not cause immediate harm but can lead to reduced engine performance and increased emissions.
Possible causes	– Defective PCV valve or regulator – Clogged or malfunctioning crankcase breather system – Vacuum leaks in the PCV system – Electrical problems with the PCV valve circuit
How to diagnose?	Verify valve operation: Ensure the PCV valve itself functions correctly. Inspect breather system: Check the crankcase breather system for blockages or clogs. Test for leaks: Use a smoke machine or similar method to identify any vacuum leaks. Electrical diagnosis: Perform electrical checks on the PCV valve circuit for any faults.

When the engine light comes on with the code P052E, it means there’s something wrong with a part of the engine that controls the ‘breathing’ of the engine – the PCV system. This system helps get rid of harmful gases inside the engine and keeps it running clean. If the valve that manages this system isn’t working right, your engine might not run efficiently, and you could see an increase in pollution. While your car might still drive, it’s a good idea to check this out soon to make sure your engine stays healthy.

How to fix P052E – learn from mechanics

I looked into P052E service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Audi

Vehicle Information 2013 Audi A6 Quattro Premium Plus 3.0L

Issue + Repair History

• MIL Lamp on
• Code P052E: Positive Crankcase Ventilation Regulator Valve Performance
• Excessive crankcase vacuum when removing oil filler cap
• Replaced oil separator assembly, connector pipe, seals/orings
• Same code and issue persisted after repairs
• Fuel trims within +/-5%, no external vacuum leaks, closed loop for both banks

What Are People Suggesting to Fix Issue

• Confirm if PCV assembly was OE and consider replacing with a known good one
• Note that newer VAG vehicles have higher vacuum, a high reading may not indicate a leak
• Ensure correct part is fitted
• Measure crankcase vacuum, check if valve regulates at correct mbar
• Check for a stuck open valve that opens to the CCV

What Was the Final Fix

• Repeated testing of the N548 valve (crankcase ventilation shut off valve) showed it began to fail after constant activation
• Replaced the N548 valve
• No returning codes or issues after one week of customer driving

Case #2: Mercedes

Vehicle Information 2015 Mercedes-Benz C300 4Matic 2.0L

Issue + Repair History

• MIL Lamp on
• Code P052E: crankcase ventilation valve faulty, actuator blocked
• Cold weather possibly contributed to the issue due to short trips and not allowing the vehicle to fully warm up
• No recurring code since the weather warmed up

What Are People Suggesting to Fix Issue

• Check freeze frame data for conditions when the code was set
• Call the dealer to check which PCV parts are commonly sold or fail
• Replace PCV vent line with the actuator
• Activate the actuator to check its function and circuit
• Replace the vent valve and the oil separator to prevent condensation issues

What Was the Final Fix

• The issue was suspected to be related to the cold weather causing condensation and possibly freezing over parts of the PCV system
• No parts were replaced as the problem did not reoccur after the weather warmed up

Case #3: Mercedes

Vehicle Information 2015 Mercedes-Benz C350 3.5L

Issue + Repair History

• MIL Lamp on
• Code P1D0313: vent valve for the crankcase has an electrical fault with an open circuit

What Are People Suggesting to Fix Issue

• Confirm if Y58/2 is the related check valve using MB wiring diagram
• Testing with wiring diagram to identify if the issue is due to an unplugged connector or an open circuit
• Check for oil in engine control unit connector or a faulty Y58/2 valve
• Possible need to replace the entire oil separator assembly if it includes the valve

What Was the Final Fix

• Faulty Partial load crankcase ventilation valve (Part A2740182201) with no continuity
• Cleared alarms and disconnected the valve to confirm fault through ECU
• New valve measured 40 Ohms resistance
• Replaced the faulty valve which resolved the issue and deactivated the MIL

Case #4: Mercedes

Vehicle Information 2017 Mercedes-Benz Metris 2.0L

Issue + Repair History

• MIL Lamp on
• Previous code for the oil flow control valve, which was resolved by replacing the harness
• Code for the PCV Valve was present, part was replaced but the code returned after a second road test

What Was Suggested

• The crankcase vent valve may be part of a long tube assembly that could be the issue; it’s known to fail and runs from the air intake elbow to behind the driver’s side motor mount bracket
• Replace engine oil separator, vent tube, and partial load ventilation valve, as they are all part of the crankcase ventilation system and can cause the code if faulty

What Was the Final Fix

• Replacing the tube from the air horn elbow down to the side of the block was the solution
• A micro filter inside the housing that was plugged was identified as the problem, considered a poor design feature

Summary The problem was solved by addressing a plugged micro filter within the crankcase ventilation system’s long tube assembly, highlighting the importance of checking the entire assembly and not just individual components when diagnosing and repairing issues related to the PCV system.

Case #5: Mercedes

Vehicle Information 2018 Mercedes-Benz C300 2.0L

Issue

• MIL Lamp on with code P052e71 – Part load crankcase vent valve malfunction, where the actuator is reported as blocked
• Diagnostic tests indicate valve operates correctly, but there is an issue with achieving the required change in crankcase vacuum

Background

• The previous dealer diagnosis of an open circuit in the part load vent valve (Y58/2) was incorrect, as the valve tests within the specified resistance range
• Difficulty in determining the correct crankcase vacuum value at idle for this engine
• Potential issue with the crankcase vent valve assembly, where a check valve might be stuck open, causing insufficient vacuum change when the shutoff valve is closed

Suggestions for Diagnosis and Repair

1. Check the entire crankcase vent valve assembly for dislodged components.
2. Replace the PCV system with the updated kit available from Mercedes-Benz.
3. Consider replacing the crankcase vent valve assembly with a remanufactured unit due to the frequency of this issue.
4. Document and compare crankcase pressure readings with a known good vehicle due to the lack of specific pressure specifications from Mercedes-Benz.
5. If the new crankcase vent valve assembly does not resolve the issue, further investigation into potential air leaks into the crankcase or blockage in the oil separator may be necessary.

Final Fix

The specific final fix for the reported issue was not detailed in the service information. However, the typical resolution involves replacing the faulty crankcase vent valve assembly with an updated part or remanufactured unit, ensuring all connections are secure and there are no leaks in the system.

Common Advice	Diagnostic Step Description
Check the entire crankcase vent valve assembly.	Inspect the vent valve assembly for dislodgement or damage, especially the check valve within the oil separator.
Replace with an updated kit from Mercedes-Benz.	Use the newer, improved crankcase ventilation parts provided by Mercedes-Benz to ensure compatibility and function.
Use remanufactured units where applicable.	Consider using a remanufactured unit to replace the faulty assembly, as this is a common practice with these parts.
Document crankcase pressure readings.	Since specific specs are not provided, compare pressure readings with a known good vehicle for reference.
Further investigation if replacement doesn’t resolve.	If replacing the vent valve doesn’t fix the issue, look for potential air leaks or blockages in the oil separator.