1991 Infiniti Q45 BaseFACTORY OEM SERVICE PROCEDURE

Retrieving Codes

NOTE: Mode II can retrieve trouble code(s) from self-diagnostic system.

Read trouble codes with either CHECK ENGINE light or Red LED inspection light on ECU. Trouble codes will flash after selecting Mode II.

Trouble codes are indicated by the number of flashes from CHECK ENGINE light or Red LED inspection light. Count the flashes. For example, 3 long (.6 second) flashes followed by 2 short (.3 second) flashes of CHECK ENGINE light or Red LED indicate a Code 32.

TROUBLE CODE IDENTIFICATION

Code System Affected Probable Cause
11 (1) Crank Angle Sensor (2) No crank signal
12  Airflow Meter Circuit Open/shorted circuit
13  Coolant Temp. Sensor Open/shorted circuit
14  Vehicle Speed Sensor (VSS) No VSS signal
21 (1) Ign. Signal Circuit (2) Open/shorted circuit
31  ECU Signals not normal
32  EGR Function (Calif.) No EGR action
33  O2 Sensor (Left Bank) Open ckt/high O2 signal
34 (1) Knock Sensor Open/shorted ckt
35  EGR Temp. Sensor (Calif.) Open/shorted ckt
43  Throttle Sensor Open/shorted ckt
45  Injector Leak (Calif.) Leak at injector(s)
46  (W/TCS) Secondary Throttle Position Sensor Open/Shorted Circuit
51  Injector Circuit (Calif.) Injector doesn't work
53  O2 Sensor (Right Bank) Open ckt/high O2 signal
54  Automatic Trans. Signal Open signal trans. control unit
55 No Malfunction Normal condition
(1) These trouble code(s) not will activate CHECK ENGINE light.
(2) Check items causing a malfunction of crank angle sensor circuit first, if Codes 11 and 21 are present at same time.
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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