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.
DTC 18, Pump Cam Reference Pulse Error: Notes
Optical sensor also provides a pump cam signal to PCM by counting pulses on sensor disk located in injection pump. Pump cam reference signal is one of the most important inputs used by PCM for timing and start of injection. DTC 18 will set when 8 cam reference pulses are missed for every crankshaft position pulse. PCM will default to backup fuel.
- This step determines if DTC 18 is result of a hard failure or an intermittent condition.
- This step checks 5-volt reference circuits.
- This step checks ground circuit.
- This step checks if sensor is sending a signal back to PCM and if an open is present in cam signal circuit.
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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.
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