Fix P0012: Mechanic’s solutions that WORKED

The code P0012: “Intake Camshaft Position Timing – Over-Retarded (Bank 1)” indicates a problem with the camshaft timing: it’s more retarded than the engine control module has commanded it to be. It’s typically linked to the efficiency of the Variable Valve Timing system, which adjusts the timing of the intake camshaft to enhance engine performance and efficiency.

P0012 quick overview

Meaning	P0012: “Intake Camshaft Position Timing – Over-Retarded (Bank 1)”
Is it serious?	Yes, it can lead to performance issues and potential damage to the engine if not addressed.
Possible causes	– Low engine oil level or poor oil quality – Faulty camshaft phaser – Worn timing chain components – Clogged oil passages – Faulty camshaft position sensor – Variable Valve Timing (VVT) solenoid failure
How to diagnose?	Check engine oil level: Ensure oil is at the proper level and quality. Inspect oil passages: Look for blockages that could affect VVT operation. Evaluate VVT solenoid: Test for proper operation and replace if defective. Assess timing components: Verify timing chain and related parts for wear. Test camshaft phaser: Ensure it functions correctly and adjusts the cam timing as needed. Scan for additional codes: Check for other codes that might give clues to the root issue. Review camshaft position sensor: Confirm the sensor’s readings are accurate.

How to fix P0012 – learn from mechanics

I looked into P0012 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: Toyota

Vehicle Information

• 2007 Toyota Camry XLE, 2.4L Engine

Issue + Repair History

• MIL illuminated, code P0012 (“A” Camshaft Position – Timing Over-Retarded (Bank 1))
• Oil level full, new oil and filter
• No damage to crank and cam sensor or wires
• Previous repairs: new cam sprocket, VVT oil control solenoid, timing chain, guides, tensioner

Suggestions to Fix Issue

• Verify hot engine oil pressure in drive
• Use scan tool to activate the OCV (Oil Control Valve) or apply external power to see if it functions and changes the idle
• Follow the diagnostic flow chart for code P0012 to pinpoint the issue
• Check if cam timing is off, possibly a tooth misalignment
• Ensure VVT gear is unlocked and not in a locked position
• Utilize scanner’s actuation feature to check timing PIDs (Parameter IDs)
• Consider replacing cam gears if defective
• Inspect for a bad OCV as it could prevent duty percent from increasing
• Use a scope to capture cam/crank sensor data to verify timing is set correctly

Final Fix

• Installed a used cylinder head, drove for 163 miles with no recurrence of the code. Mechanic speculated the previous shop may have installed the incorrect cylinder head, noting differences between Japan and North American engine versions.

Case #2: Scion

Vehicle Information

• 2006 Scion xA 1.5L, MIL Lamp on

Issue + Repair History

• Customer reported intermittent MIL for 16 months, now constant
• Failed inspection
• Code P0012: Cam position A timing over-retard bank 1
• Bulletin for camshaft timing gear replacement related to VIN

Other OBD2 Codes + Test Results

• No additional codes or test results mentioned

Suggestions to Fix Issue

• Verify proper operation of the actuator per TSB
• Check if the complete timing chain removal is necessary (confirmed it is necessary)
• Check VVT-i solenoid and screen for clogging
• Review the TSB for the correct VVT-i gear assembly replacement procedure

Final Fix

• Full timing cover and chain removal required for cam gear replacement
• Labor time discrepancy resolved: job is approximately 1-2 hours, not 5-6 as suggested by some
• The replacement process includes removing valve cover, timing chain tensioner access, marking timing positions, and following TSB procedures for gear replacement

Case #3: Hyundai

Vehicle Information:

• 2007 Hyundai Accent GS 1.6L

Issue Summary:

• MIL Lamp on with DTC P0012 (“cam over retarded”) after the vehicle gets hot.
• OCV solenoid and CVVT already replaced.
• OCV filter is clean.

Previous Related Repair History:

• Replacement of OCV solenoid.

Final Resolution:

• The newly installed OCV solenoid was faulty.
• After replacing with another new OCV solenoid, the code was resolved.

Suggested Diagnostic Steps and Considerations:

• Confirm the base engine timing is correct.
• Ensure the engine oil is of the correct weight and has been changed regularly to avoid issues with sludge that can affect VVT operation.
• Check for potential ECM/PCM software issues; reflash if necessary.
• Inspect the oil control valve coil resistance to ensure proper electrical function.
• Evaluate the use of OE equivalent filters for oil control.
• Verify timing marks on the belt and chain at the end of the camshaft.
• Investigate the wiring harness to the PCM and OCV valve for any issues.
• Question the quality of replacement parts (OEM vs. aftermarket or used).

Technical Insights:

• The performance of VVT systems is highly sensitive to oil quality and pressure.
• Proper diagnosis should include electrical and mechanical testing of VVT components.
• Software updates for the ECM/PCM can resolve various engine performance issues.
• Using OEM parts is often recommended to avoid discrepancies in part operation and compatibility.
• A thorough inspection of related wiring and connectors is crucial, as electrical faults can mimic mechanical problems.

Case #4: Volkswagen

Vehicle Information:

• 2001 Volkswagen Jetta GLS 1.8L

Issue Summary:

• The vehicle came in with the MIL on and a noise in the motor.
• Pulled code 16396 (P0012) – “camshaft position ‘A’ timing over-retarded (Bank 1)”.

Final Resolution:

• Diagnosis revealed almost no oil pressure.
• Oil pickup was found to be plugged after removing the oil pan.
• Bearings were not in good condition, and the crankshaft was damaged.
• The vehicle needed a motor job.
• The camshaft code was likely due to the lack of oil reaching the camshaft tensioner solenoid.

Diagnostic Replies and Suggestions:

• Check if the camshaft adjustment and timing are correct.
• Investigate the solenoid valve for camshaft adjustment and N205 solenoid.
• Examine the timing chain and tensioner for proper operation.
• Consider the vehicle’s maintenance history, including oil changes and oil quality.
• Use the correct diagnostic equipment and software for further analysis.
• Verify the resistance of the solenoid valve and the voltage at its terminals.
• Look into potential coverage of repairs by the manufacturer due to known issues with the engine.

Technical Insights:

• A blocked oil pickup and low oil pressure can lead to severe engine damage, affecting various components including the camshaft timing mechanism.
• The P0012 code indicates issues with camshaft timing which could be due to oil pressure problems or mechanical failures.
• Proper engine maintenance, including the use of recommended oil types and regular oil changes, is critical to prevent such issues.
• Given the mention of a manufacturer’s warranty extension, it’s advisable to check with the dealer regarding coverage for engine repairs, especially if there’s a history of regular oil services.
• Following manufacturer recommendations, such as using synthetic oil for turbocharged engines and allowing the turbo to cool down before turning off the engine, can help prolong engine life.

Case #5: Mazda

Vehicle Information

• 2008 Mazda 3 i, 2.0L engine

Issue + Repair History

• Poor idle quality, fluctuating between 750 and 500 RPM
• Replaced head gasket
• Initially had P0300 (misfire) and an unidentified accelerator-related code (cleared by mistake)
• Later, only P0012 code found (Intake Cam Over-retarded)

Suggestions to Fix Issue

• Check for vacuum leaks, especially the PCV under the intake
• For P0012 code, check cam timing with special service tool
• Clean throttle body and throttle plate
• Consider issues with cam phaser and solenoid for P0012 code
• Check the air bellows (air intake snorkle) for cracks
• Perform throttle plate position relearn with KOEO (Key On Engine Off) and KOER (Key On Engine Running) procedure
• Check oil pressure, as it might affect the phaser

Final Fix

• Cleaning the throttle body with carb cleaner resolved the idle issue.

Advice	Brief Description of Diagnostic Step
Check for vacuum leaks	Inspect the PCV under the intake and other vacuum points for leaks.
Clean the throttle body	Remove buildup from the throttle body and plate for better air flow.
Check cam timing	Use a special service tool to ensure the camshaft timing is correct.
Consider phaser and solenoid	If P0012 persists, evaluate the VVT phaser and solenoid for faults.
Inspect the air intake snorkel	Look for cracks in the air bellows which could cause air flow issues.
Perform relearn procedures	Conduct KOEO and KOER procedures to reset throttle plate position sensors.
Verify oil pressure	Low oil pressure can affect the cam phaser, which may trigger P0012.