Mechanics

Toyota OBD1 Trouble Codes

Easy step by step guide on how to gather Toyota OBD1 codes and definition table.

Step 1 - To gather trouble codes locate the diagnostic connector under the hood near passengers fender, or under the dash on the driver’s side.

Step 2 - Use a jumper wire connect the TE1 and T1 terminals (For Tercel and MR2 use the T and E1 terminals).


Toyota OBD1 Diagnostic Connector

Step 3 - Turn the ignition key to the "ON" position and observe the check engine light, count the number of times it blinks which will be the first digit of the two digit trouble code, the check engine light will pause shortly followed by the second digit of the trouble code. For example; if the check engine light blinks once and pauses followed by six blinks the trouble code number would be 16.

If no code is present the check engine light will stay on constantly, to restart code gathering turn the ignition key to the "OFF" position, wait three minutes and turn the ignition key back "ON" again. Remove the jumper wire once code gathering is complete. To clear code after the repairs have been made remove the negative battery cable for one minute and reconnect.


Code Definition Table

Code 11 Momentary interruption in power supply to ECU (electronic control unit or computer) up to 1991

Code 12 Engine revolution signal missing

Code 13 Rpm signal to ecu missing above 1000 rpm

Code 14 Igniter signal to ecu missing

Code 16 A/T control signal missing from ecu

Code 21 Main oxygen sensor signal fault

Code 22 Water temperature sensor circuit fault

Code 23 and 24 Intake air temperature signal fault

Code 25 Air/fuel ratio LEAN

Code 26 Air/fuel ratio RICH

Code 27 Sub-oxygen sensor signal or heater circuit fault

Code 28 No. 2 oxygen sensor/heater signal fault

Code 31 and 32 Air flow meter circuit or Vacuum sensor signal fault

Code 34 and 36 Turbo-charging pressure signal fault

Code 35 Altitude compensation sensor signal fault

Code 41 Throttle position circuit fault

Code 42 Vehicle speed sensor circuit

Code 43 No starter signal to the ecu

Code 51 AC signal on; DL contact off (in transmission shifter with diagnostic connector jumped)

Code 52, 53 and 55 Knock sensor fault Code 71 EGR system malfunction

Code 72 Fuel cut solenoid signal fault

Code 78 Fuel pump control signal fault

Code 81, 83, 84 and 85 TCM communication fault

AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2015-05-12)