Most modern engines use variable valve timing, where the engine computer turns the camshaft slightly ahead of or behind the crankshaft to improve power, fuel economy and emissions. A P0012 code means the bank 1 intake camshaft timing is further retarded than commanded.
This guide covers the meaning, the symptoms, the causes and the tests that find the real fault.
P0012 Code Breakdown
Every OBD-II code follows the same five-character pattern set by the SAE J2012 standard. Each character narrows down which system has the fault. This table shows what each part of the code tells you.
| Character | Meaning | What It Tells You |
|---|---|---|
| P | Powertrain | The fault is in the engine or transmission systems. |
| 0 | Generic (SAE) code | The definition is the same on every OBD-II vehicle. |
| 0 | Fuel and air metering and auxiliary emission controls | The fault involves cam timing, turbo and boost control, fuel pressure or other fuel and air metering systems. |
| 12 | Specific fault | “A” Camshaft Position Timing Over-Retarded (Bank 1) |
What the P0012 Code Means
The SAE J2012 standard defines the P0012 code as “A” Camshaft Position Timing Over-Retarded (Bank 1). A cam phaser on the end of the camshaft uses engine oil pressure to rotate the cam. An oil control valve, also called the VVT solenoid, sits near the front of the cylinder head and directs oil to one side of the phaser or the other. The engine computer pulses this valve and watches the camshaft position sensor to see where the cam actually is.
Bank 1 is the side of the engine with cylinder 1, and camshaft “A” is the intake cam on most engines. Because the system runs on engine oil, low oil, dirty oil or the wrong viscosity cause many cam timing codes. A stretched timing chain can also throw the cam out of its expected position.
This code means the bank 1 intake camshaft is further retarded than the engine computer commanded. The cam is lagging behind where it should be.
Symptoms of a Cam Timing Problem
Symptoms range from mild to obvious. Common signs of a P0012 code include:
- Check engine light on
- Rough idle or stalling
- Loss of power, especially at low speed
- Poor fuel economy
- Rattle from the front of the engine at startup
- Hard starting
What Causes the P0012 Code?
This kind of fault can come from the part, the system around it or the wiring:
- Low or dirty engine oil. The most common cause.
- Oil control valve stuck or clogged.
- Cam phaser stuck in the retarded position.
- Stretched timing chain.
- Wrong oil viscosity.
Tools You Will Need
You can do most of this testing at home with basic tools:
- OBD-II scan tool with live data and graphing
- Digital multimeter with back-probe pins
- Test light
- Wiring diagram for your vehicle
- Service manual or repair information
How to Track Down the P0012 Code
Check the oil level and condition first. Many cam timing codes come from low or dirty oil.
Check Live Data and Freeze Frame
Watch desired and actual cam position, or cam angle, in live data with the engine warm. Raise engine speed to about 2,000 rpm. Actual cam angle should follow the desired value within a few degrees.
Command the Part and Watch the Result
Use a scan tool to command the camshaft timing system, where supported, and watch whether the system responds. No response with a good command points to the part or its mechanical linkage.
Check the Oil Level and Condition
Check the oil level with the engine off on level ground. Look at the oil on the dipstick. Sludge, very dark oil or the wrong viscosity can block the small screen and passages in the oil control valve. An oil change with the correct grade fixes some of these codes.
Test the Oil Control Valve
Unplug the valve and measure its coil resistance, often about 6 to 12 ohms. Remove it and check its screen for debris. With a scan tool, command the valve on at idle. The engine should stumble or idle rough, which shows the phaser responded.
How to Fix the P0012 Code
Match the repair to what your tests found. Then clear the code and drive under the same conditions that set it.
- Change the oil and filter with the grade listed in the owner’s manual.
- Replace the oil control valve if it fails its tests or the screen is clogged.
- Repair the valve connector or wiring
- Replace the cam phaser if it sticks or rattles.
- Replace the timing chain and guides if the chain has stretched.
Common Mistakes to Avoid
These mistakes waste money or leave the real fault in place:
- Replacing the camshaft timing system without testing the system around it
- Ignoring service bulletins for your vehicle
- Ignoring low or dirty oil
- Replacing the cam sensor when the oil control valve or chain is at fault
Typical Repair Costs
Repair costs depend on the cause. This table shows typical ranges for parts and labor.
| Repair | DIY Cost | Typical Shop Cost |
|---|---|---|
| Oil and filter change | $30 to $70 | $60 to $130 |
| Oil control valve | $30 to $120 | $150 to $350 |
| Wiring repair | $10 to $40 | $100 to $250 |
| Cam phaser | $100 to $300 | $500 to $1,200 |
| Timing chain kit | $150 to $400 | $800 to $2,000 |
Is It Safe to Drive with a P0012 Code?
You can usually drive a short distance with a P0012 code, but the engine may run poorly. Check the oil level right away.
Do not ignore a rattle from the timing chain. A chain that jumps a tooth can cause serious engine damage.
Related Codes
These codes often show up with this one or point to the same system:
| Code | Meaning |
|---|---|
| P0011 | “A” Camshaft Position Timing Over-Advanced or System Performance (Bank 1) |
| P0010 | “A” Camshaft Position Actuator Circuit (Bank 1) |
| P0016 | Crankshaft Position – Camshaft Position Correlation (Bank 1 Sensor A) |
| P0335 | Crankshaft Position Sensor A Circuit Malfunction |
Getting Cam Timing Back on Target
A P0012 code points to the variable valve timing system. Low or dirty oil, a faulty oil control valve, a sticking phaser and a stretched timing chain cause most cases.
- Check the oil level and condition.
- Test the oil control valve.
- Compare desired and actual cam angle.
- Check the timing chain if the code returns.
Frequently Asked Questions
Is This a Mechanical or Electrical Problem?
It can be either. Check the wiring and the commands in live data first, since that is quick. If the camshaft timing system gets the right commands and still does not respond, the fault is mechanical.
Can Low Oil Cause This Code?
Yes. The cam phaser moves the camshaft with engine oil pressure. Low oil, sludge or the wrong viscosity can keep it from moving the way the engine computer expects, which sets cam timing codes. Check the oil first.
Will This Code Clear Itself After the Repair?
If the fault is fixed, the check engine light usually turns off after about three drive cycles in a row with no fault. The stored code stays in memory for a while longer and then erases itself. You can clear it right away with a scan tool, but that also resets the readiness monitors, so the car will need some driving before an emissions test.
Do I Need a Dealer to Fix This Code?
Not always. Most of the checks in this guide need only a scan tool, a multimeter and basic hand tools. A dealer or a well-equipped shop helps when the repair needs module programming, factory software or special tools.
Can a Basic Code Reader Diagnose This Code?
A basic reader can show the code number, but it often cannot read live data or run the tests that pin down the cause. A scan tool with live data, graphing and output tests saves a lot of guesswork.
Should I Check for Technical Service Bulletins?
Yes. Carmakers publish service bulletins for known problems, and some cover this code with updated parts or engine computer software. A dealer or a repair information service can check bulletins for your VIN before you spend money on parts.
Is This Code the Same on Every Vehicle?
Yes. It is a generic SAE code, so the definition is the same on every OBD-II vehicle. The parts that cause it and the test steps vary by make and engine, so check the service manual for your vehicle before you buy parts.