P03FF

Ignition L Control Signal Circuit High

Severity

⚠️ Medium

Can you drive?

Limited driving only, diagnose soon

Approx. repair cost

$56–167 (est.)

Symptoms

Misfire in a specific cylinder
Unstable engine idling
Reduced engine power
Increased fuel consumption
Check Engine Light Illuminates

Causes

Ignition coil malfunction
Open or short circuit in wiring harness
Poor contact in the ignition coil connectors
Engine ECU malfunction
Control circuit ground problems

How to Fix

Check the resistance of the ignition coil
Inspect the wiring harness for damage
Check connections and connectors of the ignition coil
Check the integrity of the control circuit using an oscilloscope
If necessary, replace the ignition coil or repair the wiring harness
If all elements are in good condition, check the ECU output signal

Related codes

P0300 P0301 P0302 P0303 P0351