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Home >> Audi >> 2001 >> A4 Base, 1.8 C, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 1.8L Turbo >> Diagnostic Tests >> DTC P1542/17950: Angle Sensor No. 1 Implausible Signal, DTC P1543/17951: Angle Sensor Signal No. 1 Too Small &/Or DTC P1544/17952: Angle Sensor Signal No. 1 Too Large
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DTC P1542/17950: Angle Sensor No. 1 Implausible Signal, DTC P1543/17951: Angle Sensor Signal No. 1 Too Small &/Or DTC P1544/17952: Angle Sensor Signal No. 1 Too Large

NOTE: VAS 5051 scan tool, VAG 5051/1 adapter cable and VAG 1598/31 test box are necessary to diagnose this code. Follow test equipment manufacturer's instructions for scan tool operation.

Engine Control Module (ECM) monitors angle sensors Nos. 1, 2, 3 and 4 for throttle valve position. Angle sensors are potentiometers that are located in Throttle Valve Control Module (TVCM) or Throttle Position (TP) sensor. ECM calculates throttle position based on percentage values sent by angle sensors. Angle sensors No. 1 and 2 display throttle positions from 3-97 %. Angle sensors run opposite of each other. Angle sensor No. 1 runs from 3-93 % (0-5 volts), the larger the throttle opening the higher the percentage (voltage) reading. Angle sensor No. 2 runs from 93-3 % (5-0 volts), the larger the throttle opening the smaller the percentage (voltage) reading. Angle sensor No. 3 runs from 12-97 %, the larger the throttle opening the higher the percentage (voltage) reading. Angle sensor No. 4 runs from 4-49 %, the larger the throttle opening the higher the percentage (voltage) reading.

  1. Connect VAS 5051 or equivalent scan tool to DLC. DLC is located behind cover under left side of steering column. Start engine. Using VAS 5051, from selection 1, click on function "08 - READ MEASURING VALUE BLOCK". Leave engine running. Go to next step.
  2. From scan tool, enter display group MAX. INPUT VALUE = 255. From button field 2 select function 062, for DISPLAY GROUP NUMBER 062. Press "Q" button to confirm input. Observe specified values for E-gas potentiometer voltages in display fields 1 and 2. See Figure. If displayed values are not as specified, go to next step. If displayed values are as specified, go to step  13.
  3. While observing display fields 1 and 2, press accelerator pedal to floor. Percent indication in display field 1 should rise smoothly from about 3-93 %. Percent indication in display field 2 should decrease smoothly from about 93-3 %. If angle sensors percent indications do not display as specified, go to next step. If angle sensors percent indications display as specified, go to step  13.
  4. Turn ignition off. Disconnect TVCM 6-pin harness connector. TVCM is located on throttle body. Using DVOM, measure voltage between specified terminals. See CHECKING THROTTLE VALVE CONTROL MODULE VOLTAGE  table. See Figure. If voltages are not as specified, leave TVCM harness connector disconnected and go to next step. If voltages are as specified, go to step  13.
    CHECKING THROTTLE VALVE CONTROL MODULE VOLTAGE

    Harness Connector Terminals Specified Value
    2 & Ground About 5 Volts
    2 & 6 About 5 Volts
  5. Disconnect ECM harness connectors. ECM is located in left rear corner of engine compartment, in electronics box. Connect VAG 1598/31 test box to ECM wiring harness (leave ECM disconnected). Using DVOM, check for open, short to voltage, short to ground or short to each other (pay special attention to harness connector terminals that could be loose or corroded) in specified circuits between TVCM harness connector terminals and VAG test box sockets. See CHECKING THROTTLE VALVE CONTROL MODULE CIRCUITS  table. If no problem is found, reconnect all disconnected connectors and go to next step. If problem is found, repair as necessary. After repair, go to step  13.
    CHECKING THROTTLE VALVE CONTROL MODULE CIRCUITS

    TVCM Harness Connector Terminal VAG Test Box Socket
    1 92
    2 83
    3 117
    4 84
    5 118
    6 91
    6. NOTE: Accelerator Pedal Position (APP) sensor may also be referred to as the Throttle Position (TP) sensor.
  6. Before replacing TVCM, check Accelerator Pedal Position (APP) sensor. Using VAS 5051, from selection 1, click on function "08 - READ MEASURING VALUE BLOCK". Leave engine running. Go to next step.
  7. From scan tool, enter display group MAX. INPUT VALUE = 255. From button field 2 select function 062 for DISPLAY GROUP NUMBER 062. Press "Q" button to confirm input. Observe specified values for E-gas potentiometer voltages in display fields 3 and 4. See Figure. If displayed values are not as specified, go to next step. If displayed values are as specified, go to step  11.
    8. NOTE: Indicated value in display field 3 should always be about twice as large as the value in display field 4.
  8. While observing display fields 3 and 4, press accelerator pedal to floor. Percent indication in display field 3 must rise smoothly from 12-97 %. Percent indication in display field 4 must rise smoothly from 4-49 %. If accelerator pedal position sensors percent indications do not display as specified, go to next step. If accelerator pedal position percent indications display as specified, go to step  13.
  9. Remove driver's side knee bolster. Disconnect APP 6-pin harness connector. APP is located on accelerator pedal. Turn ignition on. Using DVOM, measure voltage between specified APP harness connector terminals. See CHECKING THROTTLE POSITION SENSOR CIRCUITS  table. See Figure. If voltages are not as specified, go to next step. If voltages are as specified, go to step  13.
    CHECKING THROTTLE POSITION SENSOR CIRCUITS

    Throttle Position Sensor Harness Connector Terminals Specification
    1 & Ground About 5 Volts
    1 & 5 About 5 Volts
    2 & Ground About 5 Volts
    2 & 3 About 5 Volts
  10. Disconnect ECM harness connectors. ECM is located in left rear corner of engine compartment, in electronics box. Connect VAG 1598/31 test box to ECM wiring harness (leave ECM disconnected). Using DVOM, check for open, short to voltage, short to ground or short to each other in specified circuits between TP harness connector terminals and VAG test box sockets. See CHECKING THROTTLE POSITION SENSOR CIRCUITS  table. If problem is found, repair as necessary. After repair, go to step  13. If no problem is found, go to step  12.
    CHECKING ACCELERATOR PEDAL POSITION SENSOR CIRCUITS

    Accelerator Pedal Position Sensor Harness Connector Terminal VAG Test Box Socket
    1 72
    2 73
    3 36
    4 35
    5 33
    6 34
  11. Replace TVCM. See REMOVAL, OVERHAUL & INSTALLATION article. After repair, go to step  13.
  12. Replace APP sensor. See REMOVAL, OVERHAUL & INSTALLATION article. After repair, go to next step.
  13. Using scan tool, clear DTCs and generate a ECM readiness code. See FUNCTION 05 - CLEARING DIAGNOSTIC TROUBLE CODES  and READINESS CODE  under SELF-DIAGNOSTIC SYSTEM. Test drive vehicle. Using scan tool, retrieve DTCs. If DTC does not reset, testing is complete.
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