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: Notes
The ECM supplies a voltage of about .45 volt between circuits No 412 and 413. The oxygen sensor varies the voltage within a range of about one volt if the exhaust is rich, down to about .10 volt if exhaust is lean. The oxygen sensor is like an open circuit and produces no voltage when it is less than about 600°F (360°C). An open sensor circuit or cold sensor causes "open loop" operation.
- Code 45 is set when the oxygen sensor signal voltage on circuit No. 412 remains greater than .7 volt for 30 seconds, in "closed loop", engine time after start is one minute or more and throttle angle is greater than 2 percent.
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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.