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.
Malfunction Indicator Light
The Malfunction Indicator Light (MIL) is in the instrument cluster and labeled CHECK ENGINE. Power is available for the MIL when ignition is on or in the START position. After engine start, MIL will remain illuminated for approximately 4 seconds as a bulb test. If the MIL does not illuminate as a bulb check, bulb is damaged or MIL circuit is open. The MIL will turn on or flash when the Powertrain Control Module (PCM) detects an emission related component or system fault.
If the PCM has identified an emission related system fault, MIL will remain on after bulb check. PCM will store a corresponding Diagnostic Trouble Code (DTC). If the PCM does not send a control message to the instrument cluster, the MIL will illuminate. If MIL blinks at a steady rate, a severe misfire condition may exist. If MIL blinks erratically, an intermittent open or short may be present in MIL circuit.
In most instances the MIL is illuminated after 2 consecutive drive cycles with the malfunction present. When the MIL is illuminated, 3 consecutive drive cycles without a malfunction are necessary to turn off MIL. The stored DTC is erased after 40 engine warm-up cycles after the MIL is turned off. For diagnosis of MIL, see MALFUNCTION INDICATOR LIGHT in SYSTEM TESTS .
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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.