Code 13 - Atmosphere (Pa) Sensor

Turn ignition off. Remove hazard fuse at battery positive terminal for 10 seconds to reset ECU. Turn ignition on. Verify if "CHECK ENGINE" light is on. If not, problem is intermittent. Test drive and retest.
If "CHECK ENGINE" light is on, turn ignition off. Disconnect main wire harness from PA sensor. Turn ignition on. Measure voltage between Yellow/Red (pos.) sensor wire terminal and ground. If about 5 volts is present, go to next step. If not, repair open in Yellow/Red wire between ECU terminal and sensor. If wire is okay, substitute a known good ECU and recheck. If specified voltage is now available, replace original ECU.
Measure voltage between Yellow/Red (pos.) and Green/Black (neg.) sensor wire terminals. If about 5 volts is present, go to next step. If not, repair open or short in Green/Black wire between ECU terminal C12 and sensor. If wire is okay, substitute a known good ECU and recheck. If specified voltage is now available, replace original ECU.
Measure voltage between Red (pos.) and Green/Black (neg.) sensor wire terminals. If about 5 volts is present, go to next step. If not, check for open or short in Red wire between ECU terminal C9 and PA sensor. If wire is okay, substitute a known good ECU and recheck. If specified voltage is now available, replace original ECU.
Turn ignition off. Remove hazard fuse at battery positive terminal for 10 seconds to reset ECU. Substitute a known good PA sensor. Turn ignition on. Verify if "CHECK ENGINE" light is on and if Code 13 is indicated. If light is not on and Code 13 is not present, replace original PA sensor.
If light is on and Code 13 is present, substitute a known good ECU and recheck. If specified voltage is now available, replace original ECU.