Signal Too Low. Permanent Fault

Checking Power Cable
- Ignition OFF.
- Disconnect CO potentiometer.
- Ignition ON.
- Connect a voltmeter between CO potentiometer connector terminal 2 and ground.
- The voltmeter should read 5 Volts.

If reading is OK:
^ Proceed to: Checking CO Potentiometer section below.

If reading is incorrect:
^ Check cable between CO potentiometer terminal 2 and engine control module (ECM) # B32 for a short-circuit to ground.
^ Proceed to: Verification section below.





Checking CO Potentiometer
- Remove seal.
- Drill two holes in the plug. 2 mm (0.079 in) drill.
- Pull out plug with circlip ring pliers.
- Connect CO potentiometer.
- Start the engine and idle it.
- Go into scrolling values. Read off CO potentiometer value.
- Turn adjustment screw counter-clockwise to increase voltage.
- It should be possible to adjust voltage between 0 Volts and 5 Volts.

If reading is OK:
^ Adjust CO.
^ Proceed to: Verification section below.

If reading is incorrect:
^ Try a new CO potentiometer.
^ Proceed to: Verification section below.





Verification
After carrying out the repair, check that the fault has been remedied as follows:

- CO potentiometer, air conditioning (A/C) pressure sensor and engine control module connected.
- Erase diagnostic trouble code (DTC).
- Start the engine and idle it, wait 1 minute.
- Diagnostic trouble code (DTC) should not recur.

If reading is OK:
^ Fault corrected.

If reading is incorrect:
^ Proceed to: Fault-tracing Information section below.

Fault-tracing Information
The verification result shows that the fault persists.

- Do you want to exit fault-tracing?

Yes:
^ Fault not corrected.

No:
^ Proceed to: Checking Power Cable section above.