Faulty ignition coil with an internal short in the primary winding or driver circuit; Chafed or grounded ignition control wire between the coil and the powertrain control module; Corroded or loose connector pins at the coil or module; Failed ignition coil driver inside the powertrain control module; Aftermarket alarm or remote start wiring that has tapped into the ignition control circuit; Water intrusion into the coil-on-plug well causing a short to ground

DTC codes / P03xx · Ignition system and misfire / P03FE

P03FEIgnition L Control Signal Circuit Low

Q: What does code P03FE mean?

Ignition L Control Signal Circuit Low. P03FE indicates that the powertrain control module has detected an abnormally low voltage on the ignition control signal circuit for the engine's number one ignition coil or cylinder. The computer expects to see a pulsed signal that switches between high and low voltage as it commands the coil to fire, and a signal that stays low for too long tells the module that the circuit is shorted to ground or that the coil driver has failed.

P03FE indicates that the powertrain control module has detected an abnormally low voltage on the ignition control signal circuit for the engine's number one ignition coil or cylinder. The computer expects to see a pulsed signal that switches between high and low voltage as it commands the coil to fire, and a signal that stays low for too long tells the module that the circuit is shorted to ground or that the coil driver has failed.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Rough idle or misfire felt as shaking or stumbling, especially when the engine is cold
Loss of power or hesitation during acceleration
Increased fuel consumption because the affected cylinder is not firing efficiently
In some cases, a no-start condition if the short prevents the coil from charging

Common causes, most likely first

Faulty ignition coil with an internal short in the primary winding or driver circuit
Chafed or grounded ignition control wire between the coil and the powertrain control module
Corroded or loose connector pins at the coil or module
Failed ignition coil driver inside the powertrain control module
Aftermarket alarm or remote start wiring that has tapped into the ignition control circuit
Water intrusion into the coil-on-plug well causing a short to ground

How to diagnose and fix it

Inspect the ignition coil connector and wiring for corrosion, chafing, or loose pins, and repair as needed
Disconnect the coil and measure resistance from the control wire to ground to check for a short
Swap the suspect coil with a known-good coil from another cylinder and see if the code moves
Check for technical service bulletins or wiring diagrams specific to the vehicle before probing the module
Use a lab scope to verify the control signal pulse at the coil and at the module to isolate the fault
If the circuit tests good, replace the ignition coil and clear the code
If the signal is missing at the module, diagnose the powertrain control module and its power and ground feeds

Why a low signal does not always mean a bad coil

A shorted ignition control wire often rubs through on a bracket or heat shield, so a visual inspection of the full harness run is more productive than replacing parts.
The powertrain control module can set this code when its internal coil driver fails, which means a new coil will not fix the problem and the module may need replacement or repair.
Aftermarket remote starters and alarm systems frequently splice into ignition control wiring and create intermittent shorts that only appear when the added module is active.
A coil that tests good on a resistance check can still set this code if its internal driver circuit breaks down only when hot, so a cold resistance test is not conclusive.
This code is often stored alongside misfire codes for the same cylinder, but the misfire may be the result rather than the cause of the low control signal.

Can I keep driving with P03FE?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration and long trips because the misfire can overheat the catalytic converter and waste fuel. If the engine is running very rough or stalls, stop driving and arrange a tow.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.