P0018: Crankshaft/Camshaft Position Correlation (Bank 2 Sensor A)

Quick answer

• What the code means: The P0018 code indicates that the crankshaft position sensor and the camshaft position sensor for Bank 2, Sensor A, are reporting out-of-sync signals.
• Severity: This is a moderately severe code. While you might be able to drive a short distance, it's best to get it diagnosed promptly to prevent further engine damage.
• Most common cause: A stretched timing chain or belt.

What the P0018 code means

The P0018 diagnostic trouble code (DTC) officially stands for "Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor A)." In simpler terms, your engine's computer (ECM/PCM) is seeing a mismatch between the rotational position of the crankshaft and the camshaft on Bank 2, Sensor A. The crankshaft dictates piston movement, while the camshaft controls valve timing. These two components must remain precisely synchronized for the engine to run efficiently and correctly. When their signals don't correlate within the engine's specified parameters, the P0018 code is triggered.

Bank 2 refers to the engine bank that does not contain cylinder #1. Sensor A typically refers to the intake camshaft position sensor, though this can vary slightly by manufacturer.

Common symptoms

• Illuminated Check Engine Light
• Rough idle or stalling
• Reduced engine performance or power
• Difficulty starting the engine
• Increased fuel consumption
• Engine knocking or ticking noises
• Engine may enter "limp mode"

Common causes

1. Stretched timing chain or worn timing belt: This is the most prevalent cause. Over time, timing chains can stretch, or timing belts can wear, leading to a slight but critical misalignment between the crankshaft and camshaft.
2. Faulty camshaft position sensor: The sensor itself may be sending inaccurate signals due to internal failure or damage.
3. Faulty crankshaft position sensor: Similar to the camshaft sensor, the crankshaft sensor could be defective.
4. Incorrect timing chain/belt installation: If recent engine work was performed, the timing components might have been installed incorrectly.
5. Damaged or jumped timing chain/belt: In more severe cases, the timing chain could have jumped one or more teeth, or the belt could be severely damaged.
6. Variable Valve Timing (VVT) actuator failure: Issues with the VVT solenoids or actuators (also known as cam phasers) can prevent proper camshaft adjustment, leading to correlation errors.
7. Wiring issues: Damaged, corroded, or shorted wiring to either the crankshaft or camshaft position sensors can cause erratic signals.
8. ECM/PCM failure: While rare, a faulty engine control module can incorrectly interpret sensor signals.

How a technician diagnoses it

1. Verify the complaint and visual inspection: The technician will start by confirming the "Check Engine" light is on. They'll perform a thorough visual inspection for obvious issues like loose connectors, damaged wiring, or signs of recent engine work.
2. Scan for codes and freeze frame data: A professional scan tool will be connected to retrieve the P0018 code and any other related codes. Freeze frame data will be analyzed to understand engine conditions (RPM, engine load, temperature, etc.) when the code was set.
3. Clear codes and test drive: The technician may clear the codes and take the vehicle for a test drive to see if the P0018 code returns immediately or under specific driving conditions.
4. Live data stream analysis: The scan tool will be used to monitor live data from the crankshaft and camshaft position sensors. The technician will compare the signals for Bank 2, Sensor A, looking for discrepancies in degree readings or erratic patterns when compared to manufacturer specifications. Good values show a stable, synchronized signal within a few degrees of each other. Bad values will show significant drift, erratic spikes, or a constant offset.
5. Crankshaft and camshaft sensor testing: If live data is suspicious, the sensors themselves will be tested. This may involve checking voltage, resistance, and signal patterns using a digital multimeter or an oscilloscope. Good sensors will produce a clean, consistent waveform corresponding to engine rotation. Bad sensors might show flat lines, irregular spikes, or no signal.
6. Timing chain/belt inspection: This is often a critical step. The technician will inspect the timing chain or belt for stretch, wear, or improper tension. This may require partial disassembly of the engine front cover. A good timing chain will be taut with minimal slack; a worn one will show noticeable slack or elongated links.
7. VVT system check: If applicable, the VVT solenoids and actuators will be tested for proper operation and oil flow. This can involve activating them with the scan tool and observing camshaft angle changes.
8. Wiring integrity check: Continuity and resistance checks will be performed on the wiring harnesses for both sensors to ensure there are no open circuits, shorts, or excessive resistance.

Typical repair cost

The repair cost for a P0018 code can vary significantly based on the root cause and the vehicle's make and model:

• Camshaft or Crankshaft Position Sensor Replacement: Parts can range from $50 to $200, and labor from $100 to $300, totaling $150 to $500.
• Timing Chain/Belt Replacement: This is a much more intensive job. Parts can range from $200 to $800, and labor from $500 to $1,500, totaling $700 to $2,300 or more, especially if other components like water pump, tensioners, or guides are replaced simultaneously.
• VVT Actuator/Solenoid Replacement: Parts typically range from $100 to $400 per actuator, with labor from $150 to $500, totaling $250 to $900.
• Wiring Repair: Cost can vary widely from $50 to $300 depending on the extent of the damage.

These estimates do not include diagnostic fees, which are typically separate.

Can I keep driving with this code?

It is generally not recommended to keep driving for an extended period with a P0018 code. While some vehicles might seem to run relatively normally, the underlying issue (especially a stretched timing chain or faulty VVT system) can lead to serious engine damage if left unaddressed. Driving with incorrect valve timing can cause reduced performance, increased fuel consumption, and in severe cases, piston-to-valve contact, which can catastrophic engine failure. It's best to get it diagnosed as soon as possible.

Related codes

• P0016: Crankshaft Position - Camshaft Position Correlation (Bank 1 Sensor A)
• P0017: Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor B)
• P0019: Crankshaft Position - Camshaft Position Correlation (Bank 2 Sensor B)
• P0335: Crankshaft Position Sensor 'A' Circuit Malfunction
• P0340: Camshaft Position Sensor Circuit Malfunction (Bank 1 or single sensor)

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