1. Check the Oxygen Sensor itself:
* Visual Inspection: Look for any obvious physical damage to the sensor, such as cracks, corrosion, or broken wires. Pay close attention to the wiring harness where it connects to the sensor.
* Sensor Location: The O2 sensor is usually located in the exhaust manifold or the exhaust pipe near the manifold. Its location might be slightly different depending on the engine size. Consult a repair manual specific to your 1986 Chevy Celebrity to be certain.
2. Check the O2 Sensor Circuit:
* Wiring: Carefully inspect the wiring harness leading from the oxygen sensor to the ECM (Engine Control Module). Look for broken wires, loose connections, corrosion, or short circuits. A multimeter is helpful here to check for continuity and proper voltage.
* Connectors: Ensure the connectors at both the sensor and the ECM are clean and securely connected. Corrosion is a common culprit.
* Ground: A poor ground connection can also cause this code. Check the ground wire connected to the ECM and the engine block for corrosion or loose connections.
3. Check the ECM (Engine Control Module):
While less likely, a faulty ECM can also trigger code 45. This is a more advanced diagnostic step and usually requires specialized equipment or a trip to a mechanic. You're unlikely to find a simple solution here without specialized tools.
4. Other Potential Causes (Less Likely but Possible):
* Fuel System Issues: While not directly related to the O2 sensor, problems in the fuel system (fuel injectors, fuel pump) can indirectly affect the O2 sensor readings and trigger the code.
* Exhaust Leaks: A significant exhaust leak before the O2 sensor can affect readings and trigger a code.
Tools You'll Need:
* Repair Manual specific to your 1986 Chevrolet Celebrity (crucial for location and specifics)
* Multimeter (to check voltage, continuity, and resistance)
* Wire brush or sandpaper (to clean connectors)
* Socket wrench and possibly other hand tools (to access the O2 sensor)
Important Notes:
* Turn the ignition off and disconnect the negative battery terminal before performing any electrical tests or working near the exhaust system.
* The O2 sensor gets extremely hot when the engine is running. Avoid touching it while the engine is hot or recently running.
* If you're not comfortable working on your car's electrical system, it's best to take it to a qualified mechanic. Incorrect repairs can lead to more significant problems.
By systematically checking these areas, you should be able to identify the cause of diagnostic code 45 and repair the problem. Remember that a repair manual is invaluable for specific details and diagrams for your vehicle.
