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2008 - MX-5 - Engine

DTC P0122 [LF]



DTC P0122

TP sensor No.1 circuit low input

DETECTION CONDITION

  • If the PCM detects that the TP sensor No.1 voltage is below 0.1 V while the engine is running, the PCM determines that the TP sensor No.1 circuit has a malfunction.

    Diagnostic support note
  • This is a continuous monitor (CCM).

  • The MIL illuminates if the PCM detects the above malfunction conditions during first drive cycles.

  • PENDING CODE is available if the PCM detects the above malfunction condition.

  • FREEZE FRAME DATA is available.

  • The DTC is stored in the PCM memory.

POSSIBLE CAUSE

  • TP sensor No.1 malfunction

  • Connector or terminal malfunction

  • Short to ground in wiring harness between throttle body terminal F and PCM terminal 2AK

  • Open circuit in wiring harness between throttle body terminal F and PCM terminal 2AK

  • Open circuit in wiring harness between throttle body terminal E and PCM terminal 2AO

  • PCM malfunction


Diagnostic procedure

STEP

INSPECTION

ACTION

1

VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
  • Has FREEZE FRAME DATA been recorded?

Yes

Go to the next step.

No

Record the FREEZE FRAME DATA on the repair order, then go to the next step.

2

VERIFY RELATED REPAIR INFORMATION AVAILABILITY
  • Verify related Service Bulletins and/or on-line repair information availability.

  • Is any related repair information available?

Yes

Perform repair or diagnosis according to the available repair information.

  • If the vehicle is not repaired, go to the next step.

No

Go to the next step.

3

CLASSIFY TP SENSOR NO.1 OR WIRING HARNESS MALFUNCTION
  • Connect the M-MDS.

  • Access TP1 PID.

  • Disconnect throttle body connector.

  • Connect a jumper wire between throttle body terminals E and F (wiring harness-side).

  • Is the voltage above 4.9 V?

Yes

Go to the next step.

No

Go to Step 5.

4

INSPECT TP SENSOR NO.1

Yes

Inspect throttle body terminal E for poor connection. Repair or replace if necessary, then go to Step 8.

No

Replace the throttle body, then go to Step 8.

(See INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [LF].)

5

INSPECT POWER SUPPLY CIRCUIT VOLTAGE AT THROTTLE BODY CONNECTOR
  • Turn the ignition switch to the ON position (Engine off).

  • Measure the voltage at throttle body terminal E (wiring harness-side).

  • Is the voltage within 4.5— 5.5 V?

Yes

Go to the next step.

No

Repair or replace for an open circuit between throttle body terminal E (wiring harness-side) and PCM terminal 2AO (wiring harness-side).

Then go to Step 8.

6

VERIFY TP SENSOR NO.1 SIGNAL CIRCUIT FOR OPEN CIRCUIT
  • Turn the ignition switch off.

  • Inspect for continuity between throttle body terminal F (wiring harness-side) and PCM terminal 2AK (wiring harness-side).

  • Is there continuity?

Yes

Go to the next step.

No

Repair or replace the wiring harness, then go to Step 8.

7

VERIFY TP SENSOR NO.1 SIGNAL CIRCUIT FOR SHORT TO GROUND
  • Inspect for continuity between throttle body terminal F (wiring harness-side) and body ground.

  • Is there continuity?

Yes

Repair or replace the wiring harness, then go to the next step.

No

Go to the next step.

8

VERIFY TROUBLESHOOTING OF DTC P0122 COMPLETED
  • Make sure to reconnect all disconnected connectors.

  • Turn the ignition switch to the ON position (Engine off).

  • Clear the DTC from the PCM memory using the M-MDS.

  • Start the engine and warm it up completely.

  • Is the same DTC present?

Yes

Replace the PCM, then go to the next step.

(See PCM REMOVAL/INSTALLATION [LF].)

No

Go to the next step.

9

VERIFY AFTER REPAIR PROCEDURE

Yes

Go to the applicable DTC inspection.

(See DTC TABLE [LF].)

No

Troubleshooting completed.




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