ENGINE (DIAGNOSTICS)(H4DOTC) > Diagnostic Procedure with Diagnostic Trouble Code (DTC)

DTC P0418 SECONDARY AIR INJECTION SYSTEM CONTROL “A” CIRCUIT OPEN

DTC DETECTING CONDITION:

Immediately at fault recognition

CAUTION:

After repairing or replacing the defective part, perform the Clear Memory Mode and Inspection Mode .

WIRING DIAGRAM:

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1.CHECK HARNESS BETWEEN ECM AND SECONDARY AIR PUMP RELAY.

1) Turn the ignition switch to OFF.

2) Disconnect the connector from the ECM and secondary air pump relay.

3) Measure the resistance of the harness between the ECM and secondary air pump relay.

Connector & terminal

(B136) No. 8 — (F9) No. 13:

Is the resistance less than 1 Ω?

Repair the open circuit in harness between ECM and secondary air pump relay.

2.CHECK HARNESS BETWEEN ECM AND SECONDARY AIR PUMP RELAY.

Measure the resistance between ECM and chassis ground.

Connector & terminal

(B136) No. 8 — Chassis ground:

Is the resistance 1 MΩ or more?

Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the fault condition, and reperform the check.

NOTE:

In this case, there may be a temporary connector contact failure.

Repair ground short of the harness between the ECM and secondary air pump relay.