Fuel System Diagnostics

Locate the diagnostic unit and remove its cover. Connect selector cable to No. 2 socket. Turn ignition to "ON" position. Enter control function No. 1 (access codes) by pressing push button one time for at least one second and no more than 3 seconds. To enter control function No. 2, press push button twice for at least one second and no more than 3 seconds. To enter control function No. 3, press push button three times for at least one second and no more than 3 seconds.
Watch the Red LED and count the number of flashes in the three-flash series. The flash series are separated by a three-second interval. See Figure . Note all codes. Only three separate codes can be stored at once. If no codes are stored, the LED will flash a 1-1-1 to indicate the fuel system is operating properly.
If a fault code is received, refer to FUEL SYSTEM FAULT CODES table. Depress push button again and check for additional codes. Depress push button a third time, if necessary. If the first code repeats, there are no other codes.
The diagnostic system memory is full when three codes are present. Those three codes must be repaired before further codes can be retrieved.

NOTE: Not all codes listed in FUEL SYSTEM FAULT CODES table are used on every vehicle.

FUEL SYSTEM FAULT CODES

Code

Fault

Repair

1-1-1

No Faults

N/A

1-1-2

ECU Failure

Replace ECU

1-1-3

Short Term Fuel Trim Too Lean/ Rich

Check Injectors, Check Fuel Pressure

1-2-1

Mass Airflow Signal

⁽¹⁾ Check Airflow Meter & ⁽¹⁾ O2 Heater Resistance

1-2-2

Air Temp. Sensor Signal

⁽¹⁾ Check Sensor

1-2-3

Cool. Temp. Sensor Signal

⁽¹⁾ Check Sensor

1-3-1

Ignition System RPM Signal

⁽²⁾

1-3-2

Batt. Voltage

Check Battery, Check Charging System

1-3-3

Throttle Switch (Idle)

⁽¹⁾ Check Throttle Switch

1-5-4

EGR Flow Too High

EGR System

2-1-2

O2 Sensor Signal

Check Fuel Pump Relay, ⁽¹⁾ Check O2 Sensor Heater

2-1-3

Throttle Switch (Full Load)

⁽¹⁾ Check Throttle Switch

2-2-1

Lambda Operation

Check Intake Manifold, ⁽²⁾ Check Fuel Pressure

2-2-2

Main Relay

Check Main Relay

2-2-3

Idle Valve Signal

⁽²⁾

2-3-1

Lambda Adjustment

Check Intake Manifold, ⁽²⁾ Check Fuel Pressure

2-3-2

Lambda Adjustment

Check Intake Manifold, ⁽²⁾ Check Fuel Pressure

2-3-3

Idle Valve (Air Leak)

Check Intake Manifold, ⁽¹⁾ Check Idle Valve

3-1-1

Speedometer Signal

⁽²⁾

3-1-2

Knock/Fuel Enrichment Signal Missing

⁽²⁾

3-2-1

Cold Start Valve

Check Cold Start Valve

3-2-2

Airflow Meter Hot Wire

⁽¹⁾ Check Airflow Meter

⁽¹⁾	See SYSTEM/COMPONENT TESTS article.

⁽²⁾	See FUEL SYSTEM FAULT CODE TESTING in this article.