Freeze Frame
OBD-II trouble code

P0012

"A" Camshaft Position - Timing Over-Retarded (Bank 1)

Severity Serious Driving See conditions below System Variable camshaft timing and actuator control Applies to OBD-II engines equipped with monitored variable camshaft timing

Published · Reviewed and updated

In plain English: Camshaft A on bank one stayed too far retarded relative to the required timing. That does not automatically mean the cam sensor or timing chain has failed.

A short, gentle trip may be possible only with correct oil level, no oil-pressure warning and a quiet, smoothly running engine. Arrange prompt diagnosis. Stop for an oil-pressure warning, timing rattle, repeated stalling, severe roughness or a flashing check-engine light. Continuing with a lubrication or mechanical timing fault can damage the engine.

A diagnostic starting point: Incorrect oil level, specification or service condition. Start by asking: Are oil level, specification and service condition correct? Illustrative parts budgets span $20–$1800 USD, with diagnosis, labor and taxes extra.

Quick answers about P0012

What does P0012 mean?
Camshaft A on bank one stayed too far retarded relative to the required timing. That does not automatically mean the cam sensor or timing chain has failed.
What should I check first for P0012?
One starting point is Incorrect oil level, specification or service condition. Check the correct level and oil approval first. On hydraulic systems, unsuitable or contaminated oil can interfere with actuator operation. The code alone does not identify a failed part; follow the procedure for your vehicle.
Can I drive with P0012?
A short, gentle trip may be possible only with correct oil level, no oil-pressure warning and a quiet, smoothly running engine. Arrange prompt diagnosis. Stop for an oil-pressure warning, timing rattle, repeated stalling, severe roughness or a flashing check-engine light. Continuing with a lubrication or mechanical timing fault can damage the engine.
How much does it cost to fix P0012?
Illustrative parts budgets in this guide span $20–$1800 USD. Diagnosis, labor and taxes are extra. P0012 can lead to routine service or major timing work. Testing identifies which repair this engine actually needs.
How do I diagnose P0012?
Start with: Are oil level, specification and service condition correct? Save all codes and freeze-frame data. Identify bank one and cam A, review recent repairs and check the owner's oil-measurement procedure. Correct a verified level or service problem without overfilling. Heavy sludge or metal needs further investigation; do not assume an oil change fixes damaged hardware.

Watch the P0012 videos

Full diagnostic video · 10:54 YouTube Short · 1:12

Full walkthrough — 10:54. Watch on YouTube

What P0012 actually means

Variable valve timing changes the camshaft's phase relative to the crankshaft. In a common hydraulic design, a control valve directs pressurized engine oil to a cam phaser. Other engines use an electric timing actuator. Cam and crank signals let the computer compare desired timing with actual position. Retarded means the cam's valve events occur later than the required phase; this is not a statement about ignition timing.

P0012 sets when the bank one A cam exceeds the permitted retarded-position error under the monitor's calibrated conditions. A usually means intake, and bank one contains cylinder number one, but confirm the engine layout. Allowed error, duration, oil temperature and enable conditions vary. No single number of degrees proves this fault on every vehicle.

Illustrative oil-controlled VVT Crankshaft Cam phaser Oil control valve Routes pressurized oil Changes cam angle relative to the crank ECM requests advance Target: 20° Actual: 4° Too retarded for the target Example values, not setting thresholds
Schematic illustration; the vehicle's layout may differ. Actual cam timing stayed too far retarded. Identify why it missed the target.

Symptoms

Possible causes and what to check

This is a practical diagnostic order, not measured failure rates. Follow the tests and priorities specified for your vehicle; a code alone does not identify a failed part.

1 Incorrect oil level, specification or service condition
Check the correct level and oil approval first. On hydraulic systems, unsuitable or contaminated oil can interfere with actuator operation.
2 Low oil pressure or restricted hydraulic oil supply
A full dipstick does not prove adequate pressure at the phaser. Screens, passages or internal leakage may affect flow.
3 Sticking oil-control valve or faulty electric actuator drive
Use the test for the actual design. An electrical click or requested duty cycle does not prove correct mechanical movement.
4 Control wiring, position feedback or calibration problem
Inspect connections and related circuit codes. Implausible position data requires signal diagnosis, not automatic sensor replacement.
5 Binding or damaged cam phaser or timing actuator
An internal fault can prevent the requested movement even when the appropriate oil supply or electrical drive is present.
6 Incorrect base timing or worn timing-drive components
Rattle, correlation codes, recent timing work or model-specific guidance can move this check to the beginning of the diagnosis.

Illustrative advance request: actual cam stays behind

Illustrative graph, not a recording from your vehicle or a universal service limit. Confirm the test conditions, units and acceptance criteria in the applicable service procedure.

The useful comparison is the requested cam phase against its verified actual movement.

After checking that the engine is safe to test, graph desired and actual bank one A-cam timing using the factory procedure. Here positive values mean advance from a reference, measured in crankshaft degrees. The request rises to twenty degrees and returns. Values and timing are illustrative; verify your tool's units and sign convention.

-5.0 1.0 7.0 13.0 19.0 25.0 0 2 5 7 10 12 Advance from reference (crankshaft degrees) Seconds during the approved timing-control test Requested advance - illustrative Healthy actual advance Actual stays retarded to target
Requested advance rises; actual should follow. Actual stays behind: test supply, control and timing.

The healthy example follows the requested advance with a brief delay, settles near the target, then returns. A small transient difference is expected; the vehicle's test criteria determine whether its response is acceptable.

The red example reaches only about four degrees while twenty is requested. It remains retarded relative to that target even though the displayed number is positive. This confirms a response problem under these example conditions, but does not distinguish inadequate oil flow, electrical control, actuator damage or incorrect base timing.

Check oil level and the exact engine procedure, then compare desired and actual timing. Test the correct actuator and its supply. Move mechanical checks forward for rattle or correlation codes. Prove the failed path before buying a sensor or chain.

How to diagnose it, in order

  1. Are oil level, specification and service condition correct?
    Save all codes and freeze-frame data. Identify bank one and cam A, review recent repairs and check the owner's oil-measurement procedure. Correct a verified level or service problem without overfilling. Heavy sludge or metal needs further investigation; do not assume an oil change fixes damaged hardware.
    Yes → go to step 2
    No → Correct the verified oil issue and reassess before testing
  2. Do oil pressure, noise and timing clues allow an active test?
    A full oil level and an unlit warning lamp do not measure actual pressure. Verify it when the procedure or symptoms require. Rattle, correlation codes, poor starting or recent timing work justify earlier mechanical inspection. Follow any engine-specific requirement to check chain condition first.
    Yes → go to step 3
    No → Stop active testing and diagnose lubrication or base timing
  3. Does actual cam timing follow the requested timing correctly?
    Use the specified temperature, speed and active-test limits. Compare matching desired and actual parameters; do not compare camshaft degrees with crankshaft degrees. Verify suspect cam or crank signals and resolve relevant circuit faults. A good result now may mean the original condition was intermittent.
    Yes → Investigate the saved intermittent conditions and verify the monitor
    No → go to step 4
  4. Do the actuator control and required supply pass their tests?
    For hydraulic VVT, test the oil-control circuit, valve and specified oil path. For electric VVT, test its power, grounds and motor control instead. Follow factory inspection instructions; a click is not proof of flow. Do not apply arbitrary battery power or add a flushing chemical as a diagnostic shortcut.
    Yes → go to step 5
    No → Repair the proven electrical, oil-supply or control-valve fault
  5. Are the phaser, actuator and mechanical timing correct?
    Check actuator movement, its locking mechanism where fitted, and base timing using the proper locking tools. Inspect the chain or belt and related components as the engine procedure requires. If these pass, review signal validity, learned positions and applicable calibration information before further replacement.
    Yes → Recheck feedback, intermittent conditions and applicable learning
    No → Repair the demonstrated actuator or timing-drive fault

Confirm timing response and the completed monitor after repair. Clearing the code alone proves nothing.

What you need to do this yourself

Some links may be affiliate links. They cost you nothing extra and do not change which tools are recommended — the diagnostic order on this site is the same either way.

Illustrative repair budgets

These are rough US planning budgets, not measured repair averages or shop quotes. Parts and labor are separate; diagnosis, taxes, access and any engine damage can add substantially to the total.

Illustrative budgets in USD; labor time is shown separately
RepairParts (USD)Labor time
Specified oil and filter service
Appropriate when a service problem is verified. It cannot repair a worn chain or damaged actuator.
 $35–$120 0.5 h
Oil-control valve or accessible circuit repair
Hydraulic systems only for the valve; prove the component or wiring fault first.
 $30–$350 1.0 h
Accessible hydraulic screen or oil-path repair
Internal oil-pressure problems can require much larger repairs than this accessible-work example.
 $20–$450 2.0 h
Cam phaser or electric timing-actuator assembly
The design determines the parts and access. Some repairs require timing-drive disassembly.
 $180–$1200 5.0 h
Timing-drive kit and related hardware
A chain or belt repair requires confirmed need; internal engine damage is outside this example.
 $250–$1800 8.0 h

P0012 can lead to routine service or major timing work. Testing identifies which repair this engine actually needs.

P0012 video summary · 1:12

A brief introduction to the code and a diagnostic starting point. Use the full guide and vehicle-specific service information for the complete procedure.

Watch this Short on YouTube

Written diagnostic walkthrough

Current written guidance organized by topic. This text may include corrections made after a video was published and is not a verbatim transcript of the archived video.

Meaning and driving guidance

Code P0012. "A" Camshaft Position - Timing Over-Retarded (Bank 1).

In plain English: camshaft A on bank one stayed too far retarded relative to the required timing. That does not automatically mean the cam sensor or timing chain has failed.

A short, gentle trip may be possible only with correct oil level, no oil-pressure warning and a quiet, smoothly running engine. Arrange prompt diagnosis. Stop for an oil-pressure warning, timing rattle, repeated stalling, severe roughness or a flashing check-engine light. Continuing with a lubrication or mechanical timing fault can damage the engine.

How it is measured

Here's what your engine computer is actually measuring.

Variable valve timing changes the camshaft's phase relative to the crankshaft. In a common hydraulic design, a control valve directs pressurized engine oil to a cam phaser. Other engines use an electric timing actuator. Cam and crank signals let the computer compare desired timing with actual position. Retarded means the cam's valve events occur later than the required phase; this is not a statement about ignition timing.

P0012 sets when the bank one A cam exceeds the permitted retarded-position error under the monitor's calibrated conditions. A usually means intake, and bank one contains cylinder number one, but confirm the engine layout. Allowed error, duration, oil temperature and enable conditions vary. No single number of degrees proves this fault on every vehicle.

The code describes a timing-control result. Oil supply, actuator control, feedback and mechanical timing must be separated before parts are ordered.

Symptoms

What you'll usually notice, beyond the light itself.

Rough idle, hesitation or stalling. Valve events occurring at the wrong phase can disturb combustion. Severe symptoms make continued driving inappropriate.

Hard starting or an uneven restart. An actuator or mechanical timing problem can leave the cam in the wrong position during starting.

Weak acceleration or reduced power. The engine may not achieve the valve timing needed for normal cylinder filling, or control may be restricted.

Rattle or unusual noise near the timing drive. Noise raises concern about lubrication, an actuator or the timing drive. Do not repeatedly rev the engine to investigate it.

Sometimes only a check-engine light. An intermittent control problem may appear only at certain temperatures or operating conditions. Save the freeze frame before clearing it.

Possible causes

Here is a practical order for checking the possible causes. These are diagnostic priorities, not measured failure rates.

Check 1: Incorrect oil level, specification or service condition. Check the correct level and oil approval first. On hydraulic systems, unsuitable or contaminated oil can interfere with actuator operation.

Check 2: Low oil pressure or restricted hydraulic oil supply. A full dipstick does not prove adequate pressure at the phaser. Screens, passages or internal leakage may affect flow.

Check 3: Sticking oil-control valve or faulty electric actuator drive. Use the test for the actual design. An electrical click or requested duty cycle does not prove correct mechanical movement.

Check 4: Control wiring, position feedback or calibration problem. Inspect connections and related circuit codes. Implausible position data requires signal diagnosis, not automatic sensor replacement.

Check 5: Binding or damaged cam phaser or timing actuator. An internal fault can prevent the requested movement even when the appropriate oil supply or electrical drive is present.

Check 6: Incorrect base timing or worn timing-drive components. Rattle, correlation codes, recent timing work or model-specific guidance can move this check to the beginning of the diagnosis.

Use the test results to choose the repair. A position in this list does not prove that a part has failed.

Illustrative diagnostic pattern

The useful comparison is the requested cam phase against its verified actual movement.

After checking that the engine is safe to test, graph desired and actual bank one A-cam timing using the factory procedure. Here positive values mean advance from a reference, measured in crankshaft degrees. The request rises to twenty degrees and returns. Values and timing are illustrative; verify your tool's units and sign convention.

The healthy example follows the requested advance with a brief delay, settles near the target, then returns. A small transient difference is expected; the vehicle's test criteria determine whether its response is acceptable.

The red example reaches only about four degrees while twenty is requested. It remains retarded relative to that target even though the displayed number is positive. This confirms a response problem under these example conditions, but does not distinguish inadequate oil flow, electrical control, actuator damage or incorrect base timing.

Check oil level and the exact engine procedure, then compare desired and actual timing. Test the correct actuator and its supply. Move mechanical checks forward for rattle or correlation codes. Prove the failed path before buying a sensor or chain.

Diagnostic steps

Use the procedure for this engine. Warning signs or manufacturer guidance can require mechanical checks before actuator testing.

Step 1. Are oil level, specification and service condition correct? Save all codes and freeze-frame data. Identify bank one and cam A, review recent repairs and check the owner's oil-measurement procedure. Correct a verified level or service problem without overfilling. Heavy sludge or metal needs further investigation; do not assume an oil change fixes damaged hardware.

Step 2. Do oil pressure, noise and timing clues allow an active test? A full oil level and an unlit warning lamp do not measure actual pressure. Verify it when the procedure or symptoms require. Rattle, correlation codes, poor starting or recent timing work justify earlier mechanical inspection. Follow any engine-specific requirement to check chain condition first.

Step 3. Does actual cam timing follow the requested timing correctly? Use the specified temperature, speed and active-test limits. Compare matching desired and actual parameters; do not compare camshaft degrees with crankshaft degrees. Verify suspect cam or crank signals and resolve relevant circuit faults. A good result now may mean the original condition was intermittent.

Step 4. Do the actuator control and required supply pass their tests? For hydraulic VVT, test the oil-control circuit, valve and specified oil path. For electric VVT, test its power, grounds and motor control instead. Follow factory inspection instructions; a click is not proof of flow. Do not apply arbitrary battery power or add a flushing chemical as a diagnostic shortcut.

Step 5. Are the phaser, actuator and mechanical timing correct? Check actuator movement, its locking mechanism where fitted, and base timing using the proper locking tools. Inspect the chain or belt and related components as the engine procedure requires. If these pass, review signal validity, learned positions and applicable calibration information before further replacement.

Confirm timing response and the completed monitor after repair. Clearing the code alone proves nothing.

Illustrative repair budgets

These are rough US planning budgets, not measured repair averages or shop quotes. Parts and labor are separate; diagnosis, taxes, access and any engine damage can add substantially to the total.

Specified oil and filter service: 35 to 120 dollars in parts, plus about 0.5 hours of labor. Appropriate when a service problem is verified. It cannot repair a worn chain or damaged actuator.

Oil-control valve or accessible circuit repair: 30 to 350 dollars in parts, plus about 1.0 hours of labor. Hydraulic systems only for the valve; prove the component or wiring fault first.

Accessible hydraulic screen or oil-path repair: 20 to 450 dollars in parts, plus about 2.0 hours of labor. Internal oil-pressure problems can require much larger repairs than this accessible-work example.

Cam phaser or electric timing-actuator assembly: 180 to 1200 dollars in parts, plus about 5.0 hours of labor. The design determines the parts and access. Some repairs require timing-drive disassembly.

Timing-drive kit and related hardware: 250 to 1800 dollars in parts, plus about 8.0 hours of labor. A chain or belt repair requires confirmed need; internal engine damage is outside this example.

P0012 can lead to routine service or major timing work. Testing identifies which repair this engine actually needs.

Sources and application limits

These manufacturer documents and technical references support the discussion. A bulletin may apply only to its listed models, engines and production dates; confirm coverage before applying it.

P0010 P0011 P0016 P0022