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DTC P0121 [L3]

BME010200100233

DTC P0121 | Throttle position stuck close (lower than expected)/open (higher than expected)
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DETECTION CONDITION | • If the PCM detects that throttle valve opening angle is below 12.5% for 5 s after the following conditions are met, the PCM determines that the TP is stuck closed: MONITORING CONDITION

  - Engine coolant temperature above 80 °C {158 °F}
  - MAF sensor signal above 58.3 g/s {7.7 lb/minutes}

• If the PCM detects that throttle valve opening angle is above 50% for 5 seconds after the following conditions are met, the PCM determines that the TP is stuck open:
MONITORING CONDITION

  - Engine speed above 500 rpm
  - MAF sensor signal below 4.8 g/s {0.63 lb/min.}

Diagnostic support note
• This is a continuous monitor (CCM).
• MIL illuminates if PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
• PENDING CODE is available if PCM detects the above malfunction condition.
• FREEZE FRAME DATA is available.
• DTC is stored in the PCM memory.
POSSIBLE CAUSE | • TP sensor malfunction • Electrical corrosion in TP signal circuit • Voltage drop in constant voltage supply circuit • Voltage drop in ground circuit • MAF sensor malfunction
• PCM malfunction

Diagnostic procedure

STEP | INSPECTION | ACTION
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1 | VERIFY FREEZE FRAME DATA HAS BEEN RECORDED • Has FREEZE FRAME DATA been recorded? | Yes | Go to the next step.
No | Record FREEZE FRAME DATA on repair order, then go to the next step.
2 | VERIFY RELATED PENDING CODE OR STORED DTC • Turn the ignition switch to the ON position (Engine off). • Retrieve pending or stored DTC using WDS or equivalent. • Is DTC P0101 also retrieved? | Yes | Go to DTC P0101 troubleshooting procedure.
No | Go to the next step.
3 | VERIFY RELATED SERVICE INFORMATION AVAILABILITY • Check for related Service Information availability. • Is any related Service Information available? | Yes | Perform repair or diagnosis according to available Service Information. • If vehicle is not repaired, go to the next step.
No | Go to the next step.
4 | VERIFY CURRENT INPUT SIGNAL STATUS - IS CONCERN INTERMITTENT OR CONSTANT • Start the engine. • Access ECT, TP and MAF PIDs using WDS or equivalent. • Warm up the engine until ECT PID is above 80 °C {176 °F} • Drive the vehicle.
• Read TP PID while MAF PID is above 58.3 g/s {7.7 lb/min.}.
• Is TP PID reading above 12.5%?
Yes
Go to Step 7.
No | Go to the next step.
5 | VERIFY TP PID • Start the engine. • Access TP, MAF and RPM PIDs using WDS or equivalent. • Read TP PID while MAF PID is below 4.8 g/s {0.6 lb/min.} and RPM PID is above 500 rpm. • Is TP PID reading above 50%? | Yes | Go to Step 12.
No | Go to the next step.
6 | VERIFY CURRENT INPUT SIGNAL STATUS - IS CONCERN INTERMITTENT OR CONSTANT • Drive the vehicle and read MAF PID. • Does MAF PID change in accordance with driving condition? | Yes | Intermittent concern exists. Go to INTERMITTENT CONCERNS troubleshooting procedure. (See INTERMITTENT CONCERN TROUBLESHOOTING [L3].)
No | Inspect the MAF sensor and the related circuits and terminals. (See MASS AIR FLOW (MAF) SENSOR INSPECTION [L3].) Repair or replace as necessary, then go to Step 16.
7 | INSPECT TP SENSOR TERMINALS FOR ELECTRICAL CORROSION • Turn the ignition switch off. • Disconnect TP sensor connector • Inspect for electrical corrosion on male and female TP sensor terminals. • Is any electrical corrosion found? | Yes | Repair or replace the terminal or the TP sensor, then go to Step 11.
No | Go to the next step.
8 | VERIFY TP SENSOR • Does TP sensor resistance smoothly change while gradually opening throttle valve? | Yes | Go to the next step.
No | Replace the TP sensor, then go to Step 11.
9 | INSPECT PCM TERMINALS FOR ELECTRICAL CORROSION • Disconnect the PCM connector. • Inspect for electrical corrosion on PCM male and female terminals. • Is any electrical corrosion found? | Yes | Repair the terminal, then go to Step 11.
No | Go to the next step.
10 | INSPECT CONSTANT VOLTAGE SUPPLY AND TP SIGNAL CIRCUITS FOR VOLTAGE DROP • Turn the ignition switch to the ON position (Engine off). • Inspect the voltage between following terminals:

  - TP sensor connector terminal C (wiring harness-side) and PCM terminal 2K
  - TP sensor connector terminal B (wiring harness-side) and PCM terminal 2A

• Is the voltage approx. 0 V?
Yes
Go to the next step.
No | Inspect for rust or corrosion on PCM terminals 2A and 2K (wiring harness-side). • Repair or replace the terminal then go to the next step.
11 | VERIFY TROUBLESHOOTING OF DTC P0121 COMPLETED • Make sure to reconnect all disconnected connectors. • Start the engine. • Clear the DTC from the PCM memory using the WDS or equivalent. • Access ECT, TP and MAF PIDs using WDS or equivalent.
• Warm up the engine until ECT PID reading is above 80 °C {176°F}.
• Drive the vehicle and read TP and MAF PIDs.
• Verify PIDs reading are within specifications
MAF PID: above 58.3 g/s {7.7 lb/min.}
TP PID: above 12.5% above 5 s
• Is the PENDING CODE of same DTC present?
Yes
Replace the PCM, then go to Step 17.
No | Go to Step 17.
12 | INSPECT TP SENSOR TERMINALS FOR ELECTRICAL CORROSION • Turn the ignition switch off. • Disconnect the TP sensor connector. • Inspect for electrical corrosion on male and female TP sensor terminals. • Is any electrical corrosion found? | Yes | Repair or replace the terminal or TP sensor, then go to Step 16.
No | Go to the next step.
13 | INSPECT GROUND CIRCUIT FOR VOLTAGE DROP • Inspect the resistance between TP sensor terminal A (wiring harness-side) and body ground. • Is the resistance approx. 0 ohm ? | Yes | Go to the next step.
No | Repair or replace for rust or corrosion on PCM terminal 2H (wiring harness-side). • Repair or replace the terminal. Go to Step 16.
14 | VERIFY TP SENSOR • Does the resistance smoothly change while gradually opening throttle valve? | Yes | Go to the next step.
No | Replace the TP sensor, then go to Step 16.
15 | INSPECT PCM TERMINALS FOR ELECTRICAL CORROSION • Disconnect the PCM connector. • Inspect for electrical corrosion on the PCM and PCM connector male and female terminals. • Is any electrical corrosion found? | Yes | Repair the terminal, then go to the next step.
No | Go to the next step.
16 | VERIFY TROUBLESHOOTING OF DTC P0121 COMPLETED • Make sure to reconnect all disconnected connectors. • Start the engine. • Clear the DTC from the PCM memory using the WDS or equivalent. • Access RPM, TP and MAF PIDs using WDS or equivalent.
• Verify TP PID is reading below 50% while MAF PID is below 4.8 g/s {0.6 lb/min.} and RPM PID is above 500 rpm.
• Is the PENDING CODE of same DTC present?
Yes
Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION [L3].)
No | Go to the next step.
17 | VERIFY AFTER REPAIR PROCEDURE • Perform "After Repair Procedure". (See AFTER REPAIR PROCEDURE [L3].) • Is there any DTC present? | Yes | Go to the applicable DTC inspection. (See DTC TABLE [L3].)
No | Troubleshooting completed.