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 41, OPTI-Spark Ignition System Open Or Shorted Est CKT: Notes
Ignition system provides 2 timing inputs to PCM, high resolution (360 pulses per camshaft revolution) and low resolution (4 pulses per crankshaft revolution). PCM uses these 2 inputs to determine individual spark timing for each cylinder. Once PCM calculates ignition timing, timing signal will be sent to ignition coil driver on IC circuit. Each timing pulse received by ignition coil driver will trigger coil driver to operate ignition coil. IC signal voltage ranges from about .5 volt to 4.5 volts. If a Code 41 is set, PCM will disable fuel injectors to prevent flooding of engine.
- Determines if code is intermittent.
- This step determines if IC signal from PCM is available at ignition coil driver. IC circuit voltage should be between about .5 volt and 4.5 volts.
- Remaining steps ensure coil driver circuitry is okay. If all wiring and connections are okay, check ignition coil and ignition coil voltage supply.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.