#OBD Codes
P0012 – Intake camshaft timing over-retarded (bank 1)
Technical definition
A camshaft position (bank1). Position timing over-retarded
What does P0012 mean?
If your check engine light is on and your scanner shows the P0012 trouble code, it means the intake camshaft ("A" camshaft) is opening too late due to incorrect timing.
Camshaft is the part of your engine that controls when the intake and exhaust valves open and close, letting air in and out of the cylinders. Timing here is everything – if the intake camshaft opens too late, your engine won’t run as smoothly as it should.
Read more: What is camshaft?
What is bank 1?
Engines with V-shaped, W-shaped, and flat configurations have their cylinders split into two banks. Bank 1 always contains cylinder #1 – typically the closest to the front of the engine, near the drive belt.
If your engine has only one row of cylinders (like most inline engines), everything falls under bank 1.
V-shaped engine banks. Source: densoautoparts.com
P0012 often indicates wear in your timing components (such as a stretched chain/belt or loose tensioner) or issues with the variable valve timing (VVT) system, which controls when valves open and close. It might also indicate a bad camshaft position sensor (often called "cam sensor" for short), damaged wiring, or loose connectors.
This fault code is similar to P0015, which indicates an over-retarded exhaust cam. These problems often appear together.
Why does the camshaft position timing matter?
Most car engines operate using a four-stroke cycle:
- Intake – The intake valve opens to let air and fuel into the cylinder
- Compression – The valve closes, and the piston squeezes this mixture
- Power – The spark plug ignites the mixture, making power to push the piston down
- Exhaust – The exhaust valve opens to let out burned gases
The image below breaks down the four-stroke cycle step by step. You can see how the camshafts control the valves while the crankshaft moves the pistons:
Four-stroke engine cycles. Source: amsoil.com
When your camshaft and crankshaft get out of sync, valves open and close at the wrong times. This bad timing messes up how your engine runs.
How serious is P0012?
You should address P0012 as soon as possible. If you catch it early, it’s often a quick and inexpensive fix. But if you let it go, you could end up with major engine damage – especially in newer cars with what mechanics call "interference engines."
In these engines, pistons and valves share the same space but at different times. If timing goes wrong or a chain breaks, these parts can collide, wrecking your engine immediately. Diagnosing the issue on time could save you thousands and keep you from being stranded.
Pro tip: A good diagnostic scanner helps you catch issues like P0012 early, saving money by identifying the problem before visiting a mechanic. Learn more about what a code reader is here.
Can I still drive with P0012?
While your car might still run, driving with the P0012 code creates unnecessary risks. You'll notice poor engine performance, sluggish acceleration, rough idle, and increased fuel consumption. These issues make driving unpleasant and potentially unsafe, especially when merging onto highways or navigating heavy traffic.
Your car might also enter "limp mode," a safety feature that limits engine performance to prevent further damage. While limp mode helps you reach a repair shop, you shouldn’t rely on it for long drives or daily use.
Common symptoms of P0012
Watch for these warning signs:
- Illuminated check engine light
- Vehicle entering limp mode
- Rough engine idle
- Decreased fuel economy
- Reduced engine power
- Difficult engine starting
- Unexpected engine stalling
- Rattling engine noises
Common causes of P0012
Code P0012 appears due to:
Variable Valve Timing (VVT) system problems
- Malfunctioning VVT solenoid
- Blocked oil flow to camshaft phasers
- Low engine oil level
- Low oil pressure
- Dirty engine oil
- Wrong oil viscosity (too thick or too thin)
Mechanical issues
- Worn timing chain/belt
- Bad tensioner allowing chain/belt to become loose
- Timing chain/belt that has skipped one or more teeth on the sprocket
- Incorrectly set camshaft position after maintenance
Sensor and electrical problems
- Faulty cam position sensor
- Damaged wiring or loose connectors
- Problems with your engine control module
How to troubleshoot P0012
Use these practical tips to diagnose and fix your P0012 error:
Clear the codes and test drive
First, use your code reader to clear the P0012 fault code from your car.
- If the fault code immediately reappears: The issue is ongoing. Skip the test drive and continue troubleshooting other potential causes.
- If the codes clear successfully: Drive your car for about 15 minutes to let the engine fully warm up and observe how it behaves. After some time, repeat this process once again.
After the second test drive, scan your car again to see if the code reappears. If it does, the problem persists and needs deeper investigation.
Pro tip: During scanning, watch for other trouble codes that might help identify the problem. For example, P0022 shows the same issue on bank 2.
Check condition of timing chain/belt and tensioners
Some experienced mechanics can identify a stretched timing chain from its distinctive rattling noise, especially during cold starts. If you hear this sound, don't ignore it – a chain that jumps teeth or snaps can immediately cause major engine damage.
For cars with timing belts, you can inspect them by carefully removing the timing belt cover. A belt that feels extremely stiff or shows cracks needs replacement right away. Watch the belt as it runs – it should stay tight and straight. If it flexes or moves side to side, it could soon jump teeth, which would also cause serious engine damage.
If the P0012 code appeared after recent service work, a mechanic might have installed the timing components incorrectly. Even if the timing is off by just one tooth, the camshaft can become over-retarded.
Inspect camshaft variable timing solenoid
Sometimes, the camshaft variable timing solenoid can get stuck and fail to adjust the valve timing according to driving conditions. To inspect it, you'll need the following tools:
- A basic set of hand tools, such as a ratchet, wrenches, and sockets
- Valve cleaner
- Digital multimeter
To inspect the solenoid, follow these steps:
1. Locate the camshaft variable timing solenoid, typically mounted on the exterior of the cylinder head cover or beneath it, near the Bank 1 intake cam.
Camshaft variable timing solenoid. Source: eeuroparts.com
2. Remove the solenoid and clean it with a valve cleaner. Sometimes, dirt and gunk can prevent it from moving freely.
3. Use a multimeter to measure its resistance, which should be 5-15 Ω. If the reading falls outside this range, replace the solenoid.
If the P0012 code persists despite addressing the common causes, it might point to a more serious issue, such as a stretched timing chain, a worn timing belt, or a faulty tensioner.
How much does it cost to fix the P0012 code?
Replacing a camshaft position sensor usually costs about $200 with labor, while replacing a camshaft variable timing solenoid cost about $300-$400. If you are going to do the replacement yourself, the sensor and the solenoid are in a similar price range, around $20-$150 each.
Keep in mind that all costs might be even higher for luxury models.
Disclaimer: Advice, how-to guides, and car care tips on our blog are intended as helpful resources for general maintenance and repairs. While we strive for accuracy, the information is provided to the best of our knowledge and should be used at your own discretion and risk.
Always refer to your vehicle's owner's manual or consult a certified mechanic for specific repair details and safety procedures.
Always refer to your vehicle's owner's manual or consult a certified mechanic for specific repair details and safety procedures.
