Troubleshooting the Honda Accord Air Fuel Ratio Sensor
The air fuel ratio sensor is one of those parts Honda Accord owners don't even know they have in their car, but once they break down they certainly make their presence felt. Similar to that of the oxygen sensor, the air/fuel ratio sensor enables the car computer to measure fuel emissions more accurately which, in turn, leads to better fuel efficiency. So once the Honda Accord air fuel ratio sensor breaks down, both the fuel and emission efficiency of your vehicle will be severely affected. So if you notice that your Accord's is not running up to speed, follow these simple steps to determine if the air fuel ratio sensor is functioning normally.
Damaged electrical connections
A lot of air fuel ratio sensor problems can be sourced to faulty electrical connections. Check the electrical connectors in your Accord's sensor for dirt and grease and clean it if necessary. Also, check for cuts and other signs of damage on the wires. Make sure to keep the harness away from the exhaust as you do this to avoid damaging the connector and wires.
Over time, carbon from the fuel exhaust will start to accumulate around the air fuel ratio sensor. Using a ratchet fitted with a sensor removal socket, remove the sensor and check the tip. If the tip is coated with carbon deposits, replace it with a new one.
If the air fuel ratio sensor and its electrical connections appear to be fine, check the voltage signal coming out of the sensor using a digital voltmeter. Hook the red probe of the voltmeter to the sensor signal wire and the black probe to the engine ground and turn on the ignition. Let the engine idle for two minutes while watching the digital display of the voltmeter. Ideally, the meter should display 0.1 or 0.2 volts for a short period, followed by fluctuations between 0.1 and 0.9 volts after two or three minutes. If the sensor takes four or more minutes to fluctuate, stays fixed at a particular voltage, or goes beyond 0.9 volts, it may have gone bad and needs replacing.