P0012 — “A Camshaft Position (Bank 1) – Timing Over-Retarded.”

—

⚙️ Code Meaning

P0012 means the intake camshaft (Bank 1) is retarded (delayed) compared to the commanded timing by the ECU.
This usually points to a VVT (Variable Valve Timing) system problem — often oil control–related or mechanical timing issues.

—

🔍 Common Causes

1. Dirty or low engine oil — sludge can block oil flow to the cam phaser.

2. Faulty VVT solenoid (OCV) — sticking or electrically failing solenoid.

3. Timing chain/belt stretch or incorrect timing.

4. Camshaft Phaser stuck in retarded position.

5. Wiring or connector issues to the camshaft actuator or solenoid.

6. Oil pressure too low (bad oil pump, blocked filter, etc.).

—

🧰 Step-by-Step Diagnosis

1. Check oil condition & level

Must be clean and at proper level.

If dirty → change oil & filter with manufacturer-recommended grade.

2. Scan live data

Look at camshaft advance angle (Bank 1 intake) and desired vs actual.

Large difference indicates actuator or oil flow issue.

3. Test VVT solenoid (OCV)

Unplug and measure resistance (typically 6–12Ω).

Apply 12 V to see if solenoid moves (audible click).

If clogged → clean or replace.

4. Inspect wiring/connectors

Check for oil intrusion, corrosion, or loose pins at solenoid and ECU.

5. Mechanical timing check

If all above are fine, inspect timing chain alignment and phaser condition.

A stretched chain or misaligned timing mark can cause over-retarded timing.

6. Oil pressure test

Ensure pressure meets spec (usually >25 psi at idle).

—

🧩 Common Fixes

✅ Replace engine oil & filter (use proper viscosity).
✅ Clean or replace VVT solenoid.
✅ Repair wiring/connector to actuator.
✅ Replace cam phaser if stuck.
✅ Re-time engine if chain jumped or stretched.

—

⚠️ Symptoms You May Notice

Rough idle

Power loss

Poor fuel economy

Rattling sound on start-up

Check Engine Light (MIL) ON

Welcome to madurai car service.