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DTC P0121/16505 - TP Sensor Circuit Range/Performance Problem

NOTE: DTC is set with coolant temperature more than 158°F (70°C), engine speed 1500-3500 RPM for longer than 2 seconds and engine load more than 68% (from MAF sensor) as soon as TP sensor signal voltage is less than .96 volts (corresponds to a throttle opening less than 12 degrees).
  1. Inspect Throttle Position (TP) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory. See CLEARING CODES  . Test drive vehicle. See TEST DRIVE.
  2. Inspect Mass Airflow (MAF) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory. See CLEARING CODES  . Test drive vehicle. See TEST DRIVE.
  3. Turn ignition off. Disconnect TP sensor connector. Using a DVOM, check resistance of TP sensor. See THROTTLE POSITION (TP) SENSOR RESISTANCE  table. If resistance readings are not to specification, replace TP sensor. If resistance readings are within specification, go to next step.
    THROTTLE POSITION (TP) SENSOR RESISTANCE

    Terminals No. Ohms At Idle Ohms Wide Open Throttle
    1 & 2 1500-2600 N/A
    2 & 3 750-1300 (1) 3600 Maximum
    (1) Resistance should gradually increase as throttle opened.
  4. Turn ignition on. Using a DVOM, check voltage between TP sensor connector terminals No. 1 (B+) and 2 (ground). Check voltage between TP sensor connector terminals No. 1 (B+) and 3 (signal). Voltage should be 4.5-5.5 volts for both tests. If voltage is within specification, erase DTC memory. See CLEARING CODES  . Test drive vehicle. See TEST DRIVE. If voltage is not within specification, go to next step.
  5. Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
  6. Using DVOM, check resistance between TP sensor connector terminal No. 2 and test box socket D12. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory. See procedures under CLEARING CODES  . Test drive vehicle. See TEST DRIVE.
  7. Using DVOM, check resistance between TP sensor terminal No. 1 and test box socket A3. Maximum resistance is one ohm. If resistance is within specification, go to next step. If resistance is not within specification, repair open circuit. Erase DTC memory. See procedures under CLEARING CODES  . Test drive vehicle. See TEST DRIVE.
  8. Using DVOM, check resistance between TP sensor terminal No. 3 and test box socket A24. Maximum resistance is one ohm. If resistance is within specification, circuit is okay. Erase DTC memory. See procedures under CLEARING CODES  . Test drive vehicle. See TEST DRIVE. If resistance is not within specification, repair open circuit. Erase DTC memory. See procedures under CLEARING CODES  . Test drive vehicle. See TEST DRIVE. If an open circuit cannot be located, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING  .
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