I'm getting two error codes for my check engine light on a 1997 SE 5sp.

One code is 0509, which I found to be the Front 02 Sensor-B2

The second code is 0307, which I couldn't find reference to anywhere.

Does anyone have any idea what the second code is telling me and what I'm visually looking for to find the front o2 sensor? Thanks.

-V

 

Diagnostic Trouble Code 0509 points to a problem with the Front Heated Oxygen Sensor, Left Bank. The left cylinder bank is also called the front bank. It is cylinders 2,4,6.

The Front Heated Oxygen Sensors are installed in the Y-pipe, the part of the exhaust system which conveys exhaust gases from the exhaust manifolds to the Catalytic Converter. There is one sensor in each branch of the Y-pipe. These sensors produce a signal which varies with the amount of oxygen in the exhaust gas, as compared to the outside air. This signal is sent to the Engine Control Module which uses it to control the fuel injection system.

DTC 0509 is detected when an excessively high voltage from the sensor is sent to the ECM. Possible causes include ...
- Harness or connectors (The sensor circuit is open or shorted.)
- a defective Front Heated Oxygen Sensor.

 

Diagnostic Trouble Code 0307 points to a problem with the Engine Control Module Closed Loop Logic for the Left Bank. The left cylinder bank is also called the front bank. It is cylinders 2,4,6.

DTC 0307 is detected when the closed loop control function for the left bank does not operate even when the vehicle conditions meet the criteria (engine at normal operating temperature, etc.). Possible causes include ...
- Harness or connectors (The sensor circuit is open or shorted.)
- a defective Front Heated Oxygen Sensor sensing element.
- a defective Front Heated Oxygen Sensor heater.

 

An Oxygen Sensor looks something like a spark plug with wires running off the exposed end. It has a metal hexagonal shell like a spark plug.

It will be helpful for you to get a Chilton or Haynes repair manual for your car. Haynes is the better of the two. You can buy these books from any large bookstore or auto parts store. They may be available at your public library.

The Oxygen Sensors are mounted in the Y-pipe. That is the part of the exhaust system which conveys exhaust gases from the exhaust manifolds to the Catalytic Converter. These sensors are accessible from below the car. Replacing them is something which can be done by the home mechanic. You will need a floor jack, a pair of sturdy jackstands, and an assortment of ordinary hand tools. There is a special socket for Oxygen Sensors but it isn't an absolute requirement.

Please check the connector and wiring before spending money on a replacement Oxygen Sensor. The sensor costs about $80.

 

Thanks for the info Dan.... If I'm thinking of getting a y-pipe, you think it'd be a good idea to replace both o2 sensors since the y pipe will be out?

-V

 

Oh, and forgot to mention, after reading your post, it looks like the codes might be causing each other... and that the oxygen sensor replacement may fix both codes?

-V

 

If you determine that those Diagnostic Trouble Codes are caused by faulty Oxygen Sensors, then replace them. It will be easier to do this replacment as part of the Y-pipe installation.

 

It's not right to say "the codes are causing each other." Better to say "the codes may arise from a common cause." Yes, one fix may very well clear both codes. Don't be too quick to condemn the Oxygen Sensor. Check the connector and wiring first.

If you have the time and interest, exchange the two front Oxygen Sensors and reset the Check Engine Light. If the same DTCs come back, the problem is not the sensor. If a new pair of DTCs turn up, and they point to the right cylinder bank, the Flame Of Blame falls on the sensor.