LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Suzuki >> 2005 >> Verona EX >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine General Information And Diagnosis >> Diagnostic Information and Procedures >> DTC P0121 Throttle Position (TP) Sensor Rationality Check >> DTC Troubleshooting
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC Troubleshooting

DIAGNOSIS PROCEDURE - DTC P0121 THROTTLE POSITION (TP) SENSOR RATIONALITY CHECK

Step Action Value(s) Yes No
1 Perform an On-Board Diagnostic (OBD) System Check.
Is the system check complete?		 - Go to Step 2. Go to "ON-BOARD DIAGNOSTIC (OBD II) SYSTEM CHECK ".
2
  1. Turn the ignition switch to ON with the engine OFF.
  2. Install a scan tool.
  3. Select the Throttle Position (TP) angle parameter on the scan tool.
  4. Monitor the scan tool while pressing the accelerator pedal to the floor and then slowly releasing the pedal (repeat the procedure several times).

Does the TP angle value increase steadily when the accelerator pedal is depressed to greater than the specified value and decrease steadily when the pedal is released to less than the specified value?		 98% 1% Go to Step 3. Go to Step 5.
3 Does the scan tool display a TP voltage below the specified value when the throttle is fully closed? 0.8 V Go to Step 4. Go to Step 5.
4
  1. Turn the ignition switch to ON with the engine OFF.
  2. Review the Freeze Frame data and note the parameters.
  3. Operate the vehicle within the Freeze Frame conditions and Conditions for Setting the DTC as noted.

Does the scan tool indicate that this diagnostic ran and passed?		 - Go to Step 14. Go to Step 5.
5 Disconnect the TP sensor electrical connector.
Is the TP sensor voltage less than the specified value?		 0.5 V Go to Step 6. Go to Step 7.
6
  1. Connect a test light to the ground circuit and B+ at the terminal 8.
  2. Connect a voltmeter to the ground circuit and ground. Does the voltmeter read a voltage greater than the specified value?

Does the voltmeter read a voltage greater than the specified value?		 0.5 V Go to Step 8. Go to Step 9.
7 Check the TP sensor signal circuit, terminal 7 for a short to voltage and repair as necessary.
Is a repair necessary?		 - Go to Step 14. Go to Step 13.
8 Check the TP sensor ground circuit, terminal 8 for a poor connection or resistance at the TP sensor connector and repair as necessary.
Is a repair necessary?		 - Go to Step 14. Go to Step 12.
9 With a digital voltmeter (DVM) connected to ground, probe the 5 volt reference circuit at terminal 50.
Does the DVM display a voltage near the specified value?		 5V Go to Step 11. Go to Step 10.
10 Check for a short to voltage in the 5 volt reference circuit, terminal 50 and repair as necessary.
Is a repair necessary?		 - Go to Step 14. Go to Step 13.
11 Replace the MTIA.
Is the repair complete?		 - Go to Step 14. -
12 Check the engine control module (ECM) electrical connectors for a poor connection or resistance and repair as necessary.
Is a repair necessary?		 - Go to Step 14. Go to Step 13.
13
  1. Turn the ignition OFF.
  2. Replace the ECM.

Is the replace complete?		 - Go to Step 14. -
14
  1. Using a scan tool, clear the Diagnostic Trouble Codes (DTCs).
  2. Start the engine and idle at normal operating temperature.
  3. Operate the vehicle within the conditions for setting the DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic ran and passed?		 - Go to Step 15. Go to Step 2.
15 Check if any additional DTCs are set.
Are any DTCs displayed that have not been diagnosed?		 - Go to applicable DTC TABLE . System OK
scientia non olet · About LEMON Manuals