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.
Repair Procedures: Removal
- Shut off the High Voltage circuit.
(Refer to High Voltage Shut-Off Procedures . )
- Turn the ignition switch OFF and disconnect the auxiliary 12V negative (-) battery terminal.
- Remove the air cleaner assembly.
(Refer to Engine & Transaxle Assembly (R & I) - Optima HEV )
- Disconnect the ECM connector (A) and remove the engine room relay box (B).
- Disconnect the battery positive (+) terminal (A).
- Remove the reservoir mounting bolt (A) and coolant outlet pipe mounting bolt (B).
- Make a gap for removing the ECM bracket mounting bolt (C) by moving the battery cable (A) and the reservoir (B) as shown in the illustration below and then remove the bolt (C).
- Remove the ECM (C) by loosening the nut (A) and the bolt (B).
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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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