Fix P00AF: Mechanic’s solutions that WORKED

The code P00AF: Turbo/Super Charger Boost Control “A” Module Performance indicates a fault in the Turbo/Super Charger Boost Control “A” Module, often related to the performance of the Variable Geometry Turbo (VGT) or related components. This issue can lead to decreased engine performance, increased emissions, and potentially more serious damage if left unaddressed.

P00AF quick overview

Meaning	P00AF: Turbo/Super Charger Boost Control “A” Module Performance
Is it serious?	This code is relatively serious as it can lead to poor vehicle performance, reduced fuel efficiency, and potential damage to the turbocharger system.
Possible causes	– Faulty Variable Geometry Turbo (VGT) actuator – Sticking or seized VGT vanes – Turbocharger malfunction – Wiring or electrical issues in the turbocharger circuit – ECM software needs an update – Blocked or leaking intake/exhaust system
How to diagnose?	Check for Software Updates: Verify the vehicle’s ECM has the latest software version. Inspect Turbo Hoses: Look for any cracks, leaks, or disconnections in the turbo hoses. Test Vacuum Actuator: Ensure the vacuum actuator for the turbo holds vacuum and operates correctly. Check VGT Position: Monitor the commanded and actual positions of the VGT to identify discrepancies. Examine Turbocharger: Consider inspecting the turbo for sticking VGT vanes or other mechanical issues. Inspect Wiring: Examine the wiring and connections related to the turbocharger, particularly the VGT actuator. Monitor Boost Pressure: Use diagnostic tools to observe the turbo boost pressure and compare it to expected values. Evaluate Exhaust System: Check the exhaust system for any blockages or leaks that could affect performance.

How to fix P00AF – learn from mechanics

I looked into P00AF 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: Ram

Vehicle Information:
2014 Ram 2500 Laramie 6.7L

Issue + Repair History:

• Low power and low boost issue with intermittent stalling.
• Replaced a pre-calibrated VGT and installed a crank sensor along with a tune-up.
• Rebuilt turbocharger, but still getting P00AF code.
• No significant changes after replacing the VGT module.

Other OBD2 Codes + Test Results:

• P0299: Boost performance.
• P00AF: Boost control module performance.
• P2BAC

Suggestions to Fix Issue:

• Check for possibly plugged exhaust.
• Ensure the exhaust psi tubes, EGR cooler, EGR piping manifold, or MAP sensor are not full of carbon.
• Verify the VGT gear arm is timed correctly to the rod that moves the vanes.
• Check the wiring connections going to the turbo.
• Monitor if the VGT position matches the desired value when the issue occurs.
• Test if the exhaust brake function works before or after the derate occurs.
• Use bi-directional control to stroke the VGT actuator both cold and hot, comparing commanded and actual positions.

Final Fix:

• After verifying the exhaust was clear and rechecking the actuator, it was found that the “rebuilt” actuator’s motor was too weak to move the vanes effectively.
• Replacing the actuator with a different one resolved the issue, and the truck hasn’t had problems since.

Case #2: Ram

Vehicle Information:
2015 Ram ProMaster 3500 3.0L

Issue + Repair History:

• Truck came in for glow plug replacement.
• Since service, it intermittently derates with P00AF code.
• Replaced the gasket for the glow plugs due to a slight leak.
• Performed VGT offset learn procedure and manual regeneration.
• Replaced the boost control solenoid after further issues.

Other OBD2 Codes + Test Results:

• P00AF: Turbo boost control module A performance.

Suggestions to Fix Issue:

• Verify the current engine controller software is up to date as per TSB 18-038-15 REV. B.
• Complete leak testing of the intake/turbo plumbing system, exhaust system, and EGR system.
• Look at freeze-frame data to compare VGT commanded and actual positions when the code sets.
• Check if variable vanes are dirty and sticking, which could affect actuator performance.
• Inspect for green corrosion on circuit wires and connectors as it could be an electrical issue.

Final Fix:

• The resolution is not specified as the truck was still undergoing diagnostics and repairs at the time of the last update. The technician replaced the boost control solenoid and continued to troubleshoot.

Case #3: Volkswagen

Vehicle Information:
2009 Volkswagen Jetta TDI 2.0L

Issue + Repair History:

• Lost power while driving with the MIL lamp on.
• Service bulletin related to P00AF code suggested checking turbo hoses and vacuum actuator, which would not hold vacuum.
• Replaced the control servo for the turbo as per the bulletin.
• No significant improvement after the initial repair.

Other OBD2 Codes + Test Results:

• P00AF: Manufacturer Specific Turbo Boost Control Performance.

Suggestions to Fix Issue:

• Verify the current engine controller software as per relevant TSB and update if necessary.
• Complete leak testing of the intake/turbo plumbing system and repair any leaks found.
• Ensure the rod to actuator relationship is correct and adjust as necessary using original measurements or a boost pressure gauge.
• Look at freeze-frame data to see the VGT commanded and actual positions when the code sets.
• Consider inspecting the turbo for sticking VGT due to dirt or carbon buildup.
• Check the wiring connections to the turbo and vacuum/boost leaks.
• Confirm operation of the N75 valve for correct operation.

Final Fix:

• The turbo actuator was the problem, with turbo/actuator issues being common for this setup.
• Replaced the boost control solenoid and adjusted it to spec with special tools and advice from experts.
• Vehicle repaired and running without issue for 2 weeks after the fix.

Case #4: Mazda

Vehicle Information:
2010 Mazda 3 i 2.0L

Issue + Repair History:

• Initially towed in for no start, no crank; only dashboard lights would illuminate.
• Previously replaced Park Neutral Position Switch and starter relay.
• Recently, experienced no crank again; tested and found power at Inhibitor Switch but no ground from PCM.
• Removed aftermarket remote starting system which resolved the issue.

Other OBD2 Codes + Test Results:

• P00AF: Turbo Charger/Super Charger Boost Control A Module Performance (not turbocharged).

Suggestions to Fix Issue:

• Lube the post that the cable attaches to on the Inhibitor Switch.
• Check for spills in the console area that might affect the electrical components.
• Test for power and ground at the starter and starter signal wire.
• Try starting in neutral to check if the problem is related to the Park Neutral Position Switch.
• Inspect for corrosion on the wiring and connectors, especially around the PCM.
• Consider issues with the ignition switch or security system, particularly if the security light is flashing.
• Check for software updates or known issues via TSBs.
• Examine the Immobilizer coil’s position and secure it if loose.

Final Fix:

• Removed an aftermarket remote starting system, which was complicated and involved repairing a lot of wiring.
• The problem of intermittent no crank/no start was resolved after the system was removed and wiring restored.

Advice	Description of Diagnostic Step
Verify Software Updates	Check for the latest engine controller software as per relevant TSBs and update the PCM if necessary.
Inspect Turbo Hoses	Check all turbo hoses for cracks or leaks which might affect turbo boost performance.
Test Vacuum Actuator	Check the vacuum actuator for the turbo to ensure it holds vacuum and operates correctly.
Check VGT Position	Compare the VGT (Variable Geometry Turbo) commanded and actual positions when the code sets.
Examine Turbocharger	Consider removing the turbo to check for sticking VGT or other issues within the turbo assembly.
Inspect Wiring	Check the wiring connections to the turbo, especially the harness for the VGT actuator.
Monitor Boost Pressure	Use diagnostic tools to monitor boost pressure and ensure it matches expected values.
Check Exhaust System	Inspect the exhaust system for blockages that could affect turbo performance.
Evaluate Actuator Replacement	If replacing the actuator, ensure rod length and adjustments are correct as per specifications.