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, Ignition Signal Circuit No Signal ESA Ignition System: Notes
This ignition system does not use a vacuum advance. The ignition system sends a signal to the ECM. The ECM uses a driver to make the coil fire a spark to the distributor. This is done by a driver which pulls 12 volts from the coil low. When the 12 volts from the coil is pulled low, the ECM looks for a signal. If the signal is not present for more than 2 seconds while cranking, Code 41 will be set. If Code 42 is set at the same time, repair Code 42 first.
- This simulates a crank signal to the ECM. The ECM will then ground the ignition coil to create a spark.
- This checks voltage supply to coil.
- Check for low voltage on ignition coil. The noise suppressor may be shorted to ground.
- This checks if ECM is shorted to ground in Brown/White wire.
- High resistance in the coil could cause a low voltage.
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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.