Tech Notes:

Diagnostic Chart for Trouble Codes and Possible Causes

For Toyota's with electronic fuel injection utilizing the Toyota EFI
or TCCS engine management system.


 
ONE DIGIT TWO DIGIT POSSIBLE CAUSE OF CODE / SYMPTOM
1 None SYSTEM NORMAL
- 11
  • Loss of Power Supply to ECU

  • Ignition Switch / Circuit

  • Main Relay / Circuit

  • ECU

6 12
  • RPM Signal - No signal to ECU from Distributor
    ("Ne" OR "G") after engine has been cranked

  • Distributor  / Circuit

  • Startersignal Circuit

  • Igniter / Igniter Circuit

  • ECU

- 13
  • Same as above but after engine has run at 1000-1500-RPM

  • Distributor / Distributor Circuit

  • ECU

3 14
  • Ignition signal --NO "IGF" signal to ECU

  • Igniter / Igniter Circuit

  • Igniter and Ignition Coil / Circuit

5 21
  • Oxygen Sensor Signal / Oxygen Sensor Heater Signal

  • Open or Short in Oxygen Sensor or Oxygen Sensor Signal

4 22
  • Water Temperature Sensor Signal -- Open or Short in Water Temp. Sensor Signal

  • Water Temperature Sensor Circuit

  • Water Temperature Sensor

  • ECU

8 24
  • Intake Air Temperature Sensor Signal -- Open or Short in Intake Air Temp. Signal

  • Intake Air Temperature Circuit

  • Intake Air Temperature Sensor

  • ECU

- 25
  • Air / Fuel Ratio Lean Indicator - Lean Signal sent to ECU from O2 Sensor

  • Injector Fault(s)

  • Fuel Pressure

  • Oxygen Sensor

  • Airflow Meter or Map Sensor

  • Ignition

  • ECU

- 26
  • Air /Fuel Ratio Rich Indicator

  • Same as above

  • Cold Start Injector

- 27
  • Sub-Oxygen Sensor Circuit or Sub-Oxygen Sensor Heater Circuit

  • Sub-Oxygen Sensor / Heater Circuit

  • ECU

- 28
  • No.2 Oxygen Sensor / Oxygen Sensor Heater

  • Same as Code 21

2 31
  • Manifold and / or Airflow Meter Sensor Signal Circuit

  • Airflow Meter / Circuit

  • Manifold Pressure Sensor / Circuit

  • ECU

- 32
  • Airflow Meter Signal (Vane-Type)

  • Airflow Meter / Circuit

  • ECU

14 34
  • Turbocharger Pressure--Abnormal Turbocharger Pressure

  • Turbocharger

  • Airflow Meter /  Manifold / Turbocharger Pressure Sensor

  • Intercooler System

  • ECU

- 35
  • Turbocharger Pressure Sensor Signal

  • Turbocharger Pressure Sensor

  • ECU

7 41
  • Throttle Position Sensor Signal -- Open or Short in TPS Signal

  • TPS Sensor

  • TPS Signal / Circuit

  • ECU

9 42
  • Vehicle Speed Sensor Signal Circuit - No SPD. Signal for Several Seconds

  • While Vehicle is Operated Under Heavy Load (TPS / MAP / AIRFLOW INPUTS)

  • Speed Sensor / Circuit

  • ECU

10 43
  • Starter Signal - No "STA" Signal to ECU until Engine Speed Exceeds 800RPM

  • Ignition Switch / Circuit

  • ECU

11 51
  • Switch Signals

  • IDL (tps) Contacts Off, Neutral Start Switch Off, A/C Switch "On" Signal to ECU

  • With Diagnostic Check Connector Shorted

  • A/C Switch / Circuit

  • A/C Amplifier

  • TPS / Circuit

  • Neutral Start Switch / Circuit

  • ECU

12 52
  • Knock Sensor Signal - Open or Short in Knock Sensor Signal

  • Knock Sensor / Circuit

  • ECU

13 53
  • Knock Control Signal in ECU

  • ECU

- 71
  • EGR Valve Malfunction - Exhaust Gas Temperature Below Spec. for EGR Control

  • EGR System

  • EGR Gas Temperature Sensor / Circuit

- 72
  • Air Conditioner Compressor Relay / Relay Signal

  • A/C Compressor Relay / Circuit

  • ECU

 



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