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.
Code P023, Ignition Control Circuit Problem: Notes
Ignition spark is controlled by PCM and ignition control module. Code P023 will set if reference pulses are being received by PCM and bypass line is low, and PCM detects pulses on ignition control line. This could be caused by by-pass line shorted to voltage at distributor. Code P023 will also set if reference pulses are being received by PCM and by-pass line is high, and PCM does not detect a signal on ignition control line. This could be caused by an open or shorted to ground ignition control line or by-pass line.
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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.