Fix P0046: Mechanic’s Solutions That WORKED!

The OBD2 code P0046 is associated with the “Turbocharger Boost Control Position Performance,” indicating an issue with the position feedback or operation of the turbocharger’s control mechanisms. This code can lead to symptoms like hesitation, low power, and an illuminated malfunction indicator lamp (MIL).

It suggests that the vehicle’s turbocharger may not be functioning as intended, possibly due to mechanical failures, sensor issues, or control circuit problems.

P0046 quick overview

Meaning	P0046: Turbocharger Boost Control Position Performance
Is it serious?	Yes, as it directly affects the vehicle’s performance by impacting the turbocharger’s ability to regulate boost levels.
Possible causes	– Faulty turbocharger or components (e.g., unison ring, vein position sensor) – Incorrect assembly or parts within the turbocharger – Damaged wiring or connectors for the turbocharger control solenoid – ECM software needing an update
How to diagnose?	Inspect the turbocharger assembly for any mechanical faults or incorrect part assembly. Check the vein position sensor (VPS) and turbocharger control solenoid wiring for damage or intermittent faults. Perform a turbocharger relearn procedure to ensure proper communication between the turbo and the ECM. Ensure PCM calibration is updated to the latest software version.

How to fix P0046 – learn from mechanics

I looked into P0046 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: Chevrolet P0046

Vehicle information 2004 Chevrolet Silverado 3500 LS 6.6L (LLY Duramax)

Issue + repair history

• Hesitation, MIL Lamp on, low power
• Codes: P0046 (turbocharger boost control position performance), P2563 (unknown)
• Replaced turbo due to frozen unison ring and installed new GM vein position sensor (VPS)
• After replacement, repeated codes persisted
• VPS internally shorted; replaced with new GM part and relearned turbo position
• Turbo still not functioning correctly, unable to command boost solenoid or VPS movement with scan tool

Other OBD2 Codes + Test Results

• P0046: Turbocharger boost control position performance
• P2563: Unknown

Mechanic suggestions

• Check for proper assembly of replacement turbo; incorrect gear inside may cause malfunction
• Inspect teeth on cam and rack to ensure they are in time and providing full stroke on the VPS
• Examine wiring turbocharger position control solenoid for any damage or intermittent opens
• Perform turbocharger relearn procedure; ensure PCM calibration is at the latest level
• Contact Jasper rep to verify the quality of remanufactured parts

Final fix

• Discovered replacement turbo supplied with incorrect gear inside, preventing proper function
• Replaced turbo again with correct gear, resolving the issue

Case #2: GMC P0046

Vehicle information 2004 GMC Sierra 2500 HD SLE 6.6L Turbo

Issue + repair history

• Check engine light and cutting out under acceleration
• Codes: P0046 & P2563 for turbo control issues
• No signs of boost leakage observed
• Turbo removed, cleaned, and inspected; no significant issues found
• Tuner returned to stock, boost sensor replaced

Other OBD2 Codes + Test Results

• P0046: Turbocharger boost control position performance
• P2563: Turbo control issues

Mechanic suggestions

• Check high pressure fuel readout from the high pressure pump; if actual and desired values are not close, consider replacing the high pressure injection pump
• Verify fuel pressure under load; marginal fuel pump could be causing the issue
• Change the fuel filter, as a clogged filter can affect fuel delivery
• Check for boost pressure leaks post-turbocharger
• Perform turbo vane position sensor relearn after replacement

Final fix

• Discovered turbo vane position sensor was faulty
• Relearned turbo vane position sensor after replacement, resolving the issue

Case #3: Jeep P0046

Vehicle information 2007 Jeep Grand Cherokee Limited 3.0L Diesel

Issue + repair history

• Cuts out under load
• Codes: P0234 (turbo over boost), P0046 (turbo boost control)
• Replaced intake tube due to hole; cleared codes initially, but issue recurred after 100 miles
• Vehicle loses power under load, boost pressure starts blowing off, goes into limp mode

Other OBD2 Codes + Test Results

• P0234: Turbo over boost
• P0046: Turbo boost control

Mechanic suggestions

• Check solder joints in the boost pressure servo motor; cracked joints may cause P0046
• Verify exhaust back pressure; if exhaust can’t exit freely, it may affect boost pressure
• Test VNT turbo actuator; faulty actuator can cause overboost issues
• Log into the car with a scan tool as a 2007 ML320 to retrieve Mercedes codes; may reveal additional issues
• Pressure test the CAC (charge air cooler) system with 30 psi to detect leaks; smoke test may not be effective at lower pressure
• Inspect hot side of the turbos for hairline cracks around the wastegate flap; cracks can cause boost leaks

Final fix

• Replaced boost pressure actuator and sent turbo out for repair, resolving the issue

Diagnostic Step	Explanation
Inspect the turbocharger and components	Verify mechanical integrity and correct assembly of the turbo, especially the unison ring and VPS.
Check VPS and control solenoid wiring	Examine for damage or disconnections that could affect turbo boost control.
Perform turbocharger relearn procedure	Relearn turbo position to ensure the turbo and ECM communicate effectively.
Ensure PCM calibration update	Update the vehicle’s computer software to the latest version if necessary.
Inspect for proper assembly and correct parts	Confirm the turbocharger is correctly assembled with the right internal gears and components.