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 18, Injector Circuit: Notes
Injectors are provided voltage when ignition is on. PCM energizes injectors by providing an individual ground for each injector. Injectors are energized on the intake stroke of each cylinder. PCM continuously monitors voltage on each driver circuit. When PCM detects a voltage that is out of range, Code 18 will set.
- Injector fuses are located in the underhood electrical center.
- Performing an injector balance test will determine which injector circuit is faulty. See SYSTEM/COMPONENT TESTS - 5.7L article in this section.
- See mini-schematic to determine which fuse powers injector banks.
- When checking injector resistance, injector should be cold.
Use the Manual With the Right Hardware
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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.
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