Initial Inspection and Diagnostic Overview

If the MFI system components (sensors, ECM, injector, etc.) tail, interruption or failure to supply the proper amount of fuel for various engine operating conditions will result. The following situations can be encountered.
1. Engine is hard to start or does not start at all.
2. Unstable idle
3. Poor driveability
If any of the above conditions is noted, first perform an inspection by self-diagnosis and subsequent basic engine checks (ignition system malfunction, incorrect engine adjustment, etc.), and then inspect the MFI system components with the Scan Tool (ST).

NOTES
1) Before removing or installing any part, read the diagnostic trouble code and then dIsconnect the battery negative (-) terminal.
2) Before disconnecting the cable from battery terminal, turn the ignition switch to OFF. Removal or connection of battery cable during engine operation or while the ignition switch is ON could cause damage to the ECM.
3) The control harnesses between the ECM and heated oxygen sensor are shielded wires with the shield grounded to the body In order to prevent the influence of ignition noises and radio interference. When the shielded wire is faulty the control harness must be replaced.

SELF-DIAGNOSIS
The ECM monitors the input/output signals (some signals at all times and the others under specified conditions).
When the ECM detects that an irregularity memorize the diagnostic trouble code, and outputs the signal to the self-diagnosis output terminal.
There are 14 diagnosis items, including the normal state, and the diagnosis results can be read out with voltmeter or Scan Tool. Diagnostic trouble codes will remain in the ECM as long as battery power is maintained. The diagnostic trouble codes will, however, be erased when the battery terminal or the engine control module connector is disconnected.

NOTE
- If the sensor connector is disconnected with the ignition switch turned on, the diagnostic trouble code is memorized. In this case, disconnect the battery negative terminal (-) for 15 seconds or more, and the diagnosis memory will be erased.