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
Sensor acts like an open sensor circuit and produces no voltage when exhaust temperature is below 600°F (316°C). An open sensor circuit or cold sensor causes "open loop" operation.
Code 45 indicates a rich exhaust and diagnosis should begin with these items: fuel pressure, leaking injector, HEI shielding, canister purge saturation, coolant sensor, MAP sensor, O2 sensor contamination and TPS intermittent output.
- Test checks to see if O2 sensor is registering a rich condition. Code 45 is set when vehicle is at operating temperature (in "closed loop"), throttle angle is between 3 and 45 percent, O2 sensor signal at ECM is greater than .7 volt for 30 seconds and time since engine start is one minute or more.
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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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