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 45 - Rich Exhaust Indication
Code 45 indicates that the ECM has seen O2 sensor voltage (at ECM terminal "D7") lower than .7 volts for 30 seconds or more, 1 minute after engine start. The ECM supplies a voltage of about .45 volt between terms. "D6" and "D7". The O2 sensor varies the voltage from 1 volt (rich indication) to .10 volt (lean indication). An open sensor circuit or a bad sensor causes open loop operation.
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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.