Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Camshaft Position (CMP) Sensor
The CMP sensor detects the position of the camshaft. The CMP sensor identifies when piston number 1 is on its compression stroke. A signal is then sent to the PCM and used for synchronizing the sequential firing of the fuel injectors. Coil on plug (COP) ignition applications use the CMP sensor signal to select the correct ignition coil to fire.
Inline engines with 2 camshafts and with variable camshaft timing (VCT) are equipped with 2 CMP sensors. The second sensor identifies the exhaust camshaft position.
The 2 sensor system on inline engines use the following CMP sensor signal circuit names:
- CMP11 - bank 1, intake camshaft
- CMP12 - bank 1, exhaust camshaft
Engines with 1 camshaft per bank and with VCT are equipped with 2 CMP sensors. The second sensor identifies the camshaft position on bank 2.
The 2 sensor system on engines with 1 camshaft per bank and with VCT use the following CMP sensor signal circuit names:
- CMP11 - bank 1
- CMP21 - bank 2
Engines with 4 camshafts and with VCT are equipped with 4 CMP sensors. The 4 sensors identify the position of each camshaft.
The 4 sensor system uses the following CMP sensor signal circuit names:
- CMP11 - bank 1, intake camshaft
- CMP12 - bank 1, exhaust camshaft
- CMP21 - bank 2, intake camshaft
- CMP22 - bank 2, exhaust camshaft
There are the 2 types of CMP sensors used. The 2 pin variable reluctance sensor and the 3 pin Hall effect sensor.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.