Troubleshooting by Diagnostic Trouble Code (DTC) - DTC P0130/P0136

DESCRIPTION AND OPERATION

The ECM uses the oxygen sensor signal to maintain the air-fuel ratio near the point at which optimum fuel economy is achieved and exhaust emissions are reduced. The oxygen concentration in the exhaust gas detected by the front oxygen sensor indicates the air-fuel ratio (rich or lean) supplied to the engine cylinders. The rear oxygen sensor signal is used to evaluate the efficiency of the catalytic converter.

The ECM determines catalytic converter efficiency by comparing the rear oxygen sensor signal with the front oxygen sensor signal.

A normal oxygen sensor signal will fluctuate around 500 mV (above or below), and the front oxygen sensor signal frequency will be at least 5 Hz at 2500 rpm. Due to the action of the catalytic converter, the rear oxygen sensor signal frequency will be lower than the front oxygen sensor signal frequency. If the rear oxygen sensor signal is the same as the front oxygen sensor signal for an extended period, this indicates deterioration of catalytic converter efficiency or a fault in the fuel system.

DTC SET CONDITIONS

[For DTC P0130] After the engine is started, the ECM checks the front oxygen sensor every 5 seconds during a driving cycle. If, during two driving cycles, the front oxygen sensor signal is outside the range of 0 - 380 mV while the rear oxygen sensor signal is greater than 350 mV, the ECM will store the above DTC and illuminate the MIL.

This DTC indicates that the ECM has detected abnormal operation of the front oxygen sensor.

[For DTC P0136] When the Multi-Port Fuel Injection (MFI) system is performing closed-loop air-fuel ratio control and the engine has been operating in this mode for 3 minutes, the ECM checks the rear oxygen sensor signal. If, during two driving cycles, the rear oxygen sensor signal is outside the range of 400 - 500 mV, the ECM will store the above DTC and illuminate the MIL. This DTC indicates an abnormal oxygen concentration measured by the rear oxygen sensor or the ECM after the engine has operated for 3 minutes following warm-up.

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECTION PROCEDURE