DTC P1630/18038: Throttle Position Sensor Signal Too Small, DTC P1631/18039: Throttle Position Sensor Signal Too Large, DTC P1633/18041: Accelerator Pedal Position Sender No. 2 Signal To Small &/Or DTC P1634/18042: Accelerator Pedal Position Sender No. 2 Signal To Large

ECM monitors Throttle Position (TP) sensor and Accelerator Pedal Position (APP) sensor No. 2 for accelerator pedal position. Both sensors are potentiometers that are located in accelerator pedal housing.

1. Connect VAS 5051 or equivalent scan tool to DLC. DLC is located behind cover under left side of steering column. Turn ignition on. Using scan tool, from selection 1, click on function "08 - READ MEASURING VALUE BLOCK". Go to next step.
2. Using 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 Fig 1. If displayed values are not as specified, go to next step. If displayed values are as specified, go to step  7.
NOTE: ECM calculates voltage values of angle sensors in percent relative to 5 volts, scan tool displays voltage as a percentage value. Indicated value in display field 3 should always be about twice as large as display field 4.
3. While observing display fields 3 and 4, press accelerator pedal to floor. Percent indication in display field 3 should rise smoothly from about 12 to 97 %. Percent indication in display field 4 should rise smoothly from about 4 to 49 %. 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  7.
4. Turn ignition off. Remove driver's side knee bolster. Disconnect APP sensor 6-pin harness connector. APP is located on accelerator pedal. Using DVOM, measure voltage between specified terminals. See CHECKING ACCELERATOR PEDAL POSITION SENSOR VOLTAGES  table. See Figure. If voltages are not as specified, leave APP sensor harness connector disconnected and go to next step. If voltages are as specified, go to step  7.
   CHECKING ACCELERATOR PEDAL POSITION SENSOR VOLTAGES
   
   

   Accelerator Pedal Position Sensor Harness Connector Terminals	Specified Value
   1 & Ground	About 5 Volts
   1 & 5	About 5 Volts
   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 APP sensor harness connector terminals and VAG test box sockets. See CHECKING ACCELERATOR PEDAL POSITION SENSOR CIRCUITS  table. See Figure. If no problem is found, go to next step. If problem is found, repair as necessary. After repair, go to step  7.
   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

6. Replace APP. See REMOVAL, OVERHAUL & INSTALLATION article. After repair, go to step  7.
7. 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.

Fig 1: Display Group 62: E-Gas Potentiometers Voltages

Courtesy of AUDI OF AMERICA, INC.