Check HO2S for poor connection or loose terminal.

Check if HO2S is ensurely installed.

Is the conditions of HO2S normal ?

	▶ Go to "Check the Signal waveform of HO2S" as follows.
	▶ Repair it and then go to "Verification of Vehicle Repair" procedure.

IG "OFF" and connect HO2S connector.

Engine start.

After warming-up, monitor signal waveform of HO2S with scantool.

Fig.1) Normal waveforms of front HO2S(the upper) and rear HO2S(the lower) (chassis ground used)

Fig.2) Normal waveforms of front HO2S(the upper) and rear HO2S(the lower) (sensor ground used)

Is the sensor switching properly?

	▶ Go to "Check fuel filter" as follows.
	▶ Substitute with a known - good HO2S and check for proper operation. If the problem is corrected, go to "Verification of Vehicle Repair" procedure.

IG "OFF" and disconnect the fuel pump connector.

Start the engine and wait until fuel in fuel line is exhausted. After the engine stalls, IG "OFF"

Remove the fuel pump assembly.

Check the fuel filter for clogging by dust, a foreign substance.

Is the fuel filter O.K.?

	▶ Substitute with a known - good ECM and check for proper operation. If the problem is corrected, replace ECM and go to "Verification of Vehicle Repair" procedure. note There is a memory reset function on scantool that can erase optional parts automatically detected and memorized by ECM. Before or after testing ECM on the vehicle, use this function to reuse the ECM on the others
	▶ Substitute with a known - good fuel filter and check for proper operation. If the problem is corrected, go to "Verification of Vehicle Repair" procedure.