CMP Sensor Signal Erratic (Nissan)
What does P1667 mean?
The P1667 code means the vehicle's onboard diagnostic system has detected: CMP Sensor Signal Erratic (Nissan). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Engine misfires or rough running
- Hard starting or no start condition
- Stalling at idle
- Reduced engine power
Probable Causes (Ranked by Likelihood)
- Faulty camshaft position sensor Very High
- Damaged reluctor ring on camshaft High
- Corroded or damaged sensor connector Moderate
- Timing chain stretch affecting cam timing Moderate
Step-by-Step Diagnostic Procedure
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Read freeze frame data to determine engine conditions when the code set.
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Inspect CMP sensor connector for oil contamination, corrosion, or loose pins.
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Measure CMP sensor resistance per Nissan specifications (typically 1000-2000 ohms).
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View CMP sensor waveform on an oscilloscope while cranking; look for consistent pattern.
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Check timing chain tension and look for excessive slack that may alter the CMP signal.
Frequently Asked Questions
Can I drive with an erratic CMP signal?
Short distances only. An erratic camshaft position signal can cause misfires, stalling, and potential catalytic converter damage from unburned fuel.
Is this related to the timing chain issue on Nissan VQ engines?
It can be. VQ35DE and VQ40DE engines are known for timing chain stretch, which can alter the CMP signal pattern and trigger this code.
Should I replace both CMP sensors?
V6 Nissan engines have two CMP sensors (one per bank). If one fails, it is advisable to replace both since they are the same age.