P0018 Trouble Code: What It Means and How to Fix It

Understanding and Fixing a P0018 Trouble Code

If your check engine light pops up and you find a P0018 Crankshaft-Camshaft Correlation Error code, you’re most likely wondering where to start your diagnosis. In this article, I’ll explain exactly what a P0018 trouble code means and how to attack the diagnosis. But first, I have to warn you not to ignore this code. A P0018 code represents a serious fault and continuing to drive without fixing the problem can lead to poor engine performance, rough idling, or even catastrophic engine failure.

What A P0018 Trouble Code Means

The P0018 trouble code stands for Crankshaft Position – Camshaft Position Correlation (Bank 2 Sensor A). Bank 2 is the bank of cylinders NOT containing the #1 cylinder. Sensor A refers to the camshaft controlling the intake valves. Sensor B refers to the camshaft controlling the exhaust valves. Simply put, a P0018 code means that the crankshaft and camshaft aren’t where the ECM expects them to be. Here’s how the ECM comes to that conclusion:

1) The ECM knows the exact location of the crankshaft based on input from the crankshaft position sensor (CKP).
2) The ECM knows the exact location of the camshaft based on input from the camshaft position sensor (CMP).
3) Based on driver demands, the ECM commands a specified amount of camshaft advance or retard by pulsing the oil control solenoid.
4) The ECM monitors the actual camshaft advance or retard by again reading the input from the CMP.
5) If the actual camshaft position doesn’t match the commanded position, the ECM knows the camshaft and crankshaft aren’t in the expected location, the engine is out of synch and the ECM sets a P0018 trouble code.

The Most Common Causes of a P0018 Trouble Code

1. Engine Oil Issues— The Variable Valve Timing (VVT) system depends on clean, properly pressurized oil to function correctly. If the oil level is low, contaminated with sludge, or the wrong viscosity, it can cause the cam phaser to malfunction, leading to timing misalignment.
2. Clogged or Malfunctioning VVT Solenoid – The VVT solenoid regulates oil flow into the camshaft phaser. If its solenoid screen is clogged with sludge or debris, it won’t properly control oil flow, preventing the camshaft from advancing or retarding. Additionally, the solenoid can fail due to electrical issues or a worn-out spool valve inside the unit.
3. Worn or Malfunctioning Camshaft Phaser – The cam phaser itself has no electronic components; it relies entirely on oil pressure to adjust timing. If it isn’t getting the right amount of oil or the correct oil pressure, it won’t operate properly. Over time, the phaser can also wear out internally, leading to improper camshaft timing and triggering a P0018 code.
4. Stretched or Worn Timing Chain/Belt – Over time, the timing chain (or belt) can stretch or wear, throwing the camshaft and crankshaft out of sync. This is a common issue in high-mileage vehicles or vehicles with neglected oil changes and can cause severe engine timing issues if left unaddressed.
5. Incorrect Timing Chain Installation – If the timing chain was recently replaced but installed incorrectly, the camshaft and crankshaft won’t be properly aligned, leading to a P0018 error. This is especially common after an engine rebuild or major timing service.
6. Faulty Camshaft or Crankshaft Position Sensors – The Camshaft Position Sensor (CMP) and Crankshaft Position Sensor (CKP) provide timing data to the Engine Control Module (ECM). If one of these sensors fails or is misaligned, the ECM will receive incorrect timing information, which can trigger a P0018 code even if the mechanical timing is correct. NOTE: This is the least likely cause of a P0018 code.
7. ECM or Wiring Problems— Though rare, a malfunctioning ECM  or damaged wiring leading to the CMP or CKP sensors can cause timing correlation errors. If all other mechanical issues have been ruled out, corrupted connectors, frayed wires, or electrical shorts should be inspected.

How to Diagnose and Fix P0018 as a DIYer

If you’re comfortable working on your car, you can diagnose and fix the P0018 trouble code with some basic tools and mechanical knowledge. Follow these steps to troubleshoot the problem.

Step 1: Check for Other Codes— Use an OBD-II scanner to check for additional trouble codes. If you also see P0017, P0011, or P0014, you might have a bigger issue with the timing system.
Step 2: Inspect the Engine Oil— Check the oil level and condition.
• If your oil level is low, top it off, erase the codes, and see if they come back.
• If you’ve gone too long between oil changes, get an oil change. Then, clear the codes and see if they come back. Remember, clean oil and oil at the correct level are critical for the VVT system to work properly.
• If you’ve used the wrong viscosity oil, change it to the recommended viscosity, clear the codes, and see if the code comes back.
Step 3: Check the oil control valve and VVT solenoids for leaks— Some carmakers use an oil pressure sensor near the VVT solenoid. The sensor contains a rubber diaphragm and a sensing element. If the diaphragm leaks, the pressure loss prevents the VVT system from operating properly. The same applies to the VVT solenoid; check first for leaks.

Step 3: Test the Electrical Connections at the VVT Solenoid and Oil Pressure Switch (if equipped)— 
• Remove the electrical connector to the solenoid/switch and check for corrosion.
• Using a wiring diagram, shop manual, and a multimeter, check for good power and ground.
• Using a multimeter check for proper resistance, short to power and short to ground in the VVT solenoid
Step 4: Remove the VVT solenoid and check for debris—A clogged filter screen in the VVT solenoid is a common cause of a P0018 trouble code. If you find debris or sludge, that’s a sign you’re driving too long on your oil. Clean the screen and change your oil and filter before starting the engine. Clear the codes and see if they return. If they do, check the screen again. If you find more debris, clean it and drive more to filter your oil longer.
NOTE: If you have access to a professional scan tool, you can also test the VVT operation using the actuator test in the scan tool. Activate the VVT solenoid while the engine is running. If the engine hesitates, it means the solenoid is functioning. If the screen isn’t clogged, replace the solenoid.
Step 5: Check the Camshaft Phaser— A failing phaser will often cause a metallic rattling sound, often heard at startup or during acceleration. Use a mechanic stethoscope to listen to each phaser for a rattling sound during startup.
Step 6: Check the timing chain/belt for wear— Locate the camshaft position sensor (CMP) and crankshaft position sensor (CKP) on your engine.
Unplug and inspect the wiring harness for loose connections or corrosion.

When to Seek Professional Help

If you’ve checked the oil, sensors, and solenoids but still have a P0018 code, the issue may be more complex—such as a failing timing chain, bent camshaft, or internal engine failure. In these cases, it’s best to consult a professional mechanic to avoid costly mistakes.

©, 2025 Rick Muscoplat