Throttle Position Sensor 1

P1121
430 Throttle Position Sensor 1 - Signal Implausible

P1121
430 Throttle Position Sensor 1 - Below Limit

P1121
430 Throttle Position Sensor 1 - Above Limit

Function
The position of the throttle valve is measured by two potentiometers. Potentiometer 1 features a rising characteristic, potentiometer 2 a falling characteristic.
The actual throttle valve angle is calculated as a function of the momentary potentiometer voltage and the learned potentiometer voltages at the lower mechanical stop.
If the two potentiometer voltages do not match, the relative air charge is used to decide which potentiometer is displaying the correct signal.

Diagnosis conditions
- Engine running

Wiring Diagram:

Diagnosis Procedure:

1 Check voltage supply to throttle motor actuator.












1. Connect special tool 9637.
2. Connect engine tester (oscilloscope) to pin III/42 (positive) and pin III/43 (negative).
Use special input.
3. Switch on the ignition.
The signal shown in the diagram should appear
4. Fully depress accelerator pedal.
The signal shown in the diagram should appear

2 Perform adaptation.

1. Switch on the ignition.
2. Wait one minute. Do not press the accelerator.
3. Switch off the ignition for at least 10 seconds.
4. Read out the fault memory.

3 Check voltage supply to throttle position sensor.

1. Connect special tool 9637 to wiring harness (DME control module connector).
2. Connect voltmeter to pin III/10 (positive) and pin III/25.
Switch on the ignition.
Display: approx. 5 V

4 Check voltage values of throttle position sensor 1.

1. Connect special tool 9637.
2. Connect voltmeter to pin III/24 (positive) and pin III/25 (negative).
Switch on the ignition.
Display: approx. 0.7 - 0.9 V

Fully depress accelerator pedal.
Display: approx. 4.1 - 4.5 V

5 Check wiring from throttle part to DME control module for continuity or short circuit to B+ or ground.


NOTE: The wires to the throttle part are routed via connector X 59/2.







1. Separate disconnection point to throttle part.
2. Connect special tool 9637 to wiring harness (DME control module connector).
3. Connect ohmmeter to disconnection point, pin 1, and special tool 9637, pin III/43.
Display: 0 - 5 ohms
4. Connect ohmmeter to disconnection point, pin 2, and special tool 9637, pin III/25.
Display: 0 - 5 ohms
5. Connect ohmmeter to disconnection point, pin 3, and special tool 9637, pin III/10.
Display: 0 - 5 ohms
6. Connect ohmmeter to disconnection point, pin 4, and special tool 9637, pin III/42.
Display: 0 - 5 ohms
7. Connect ohmmeter to disconnection point, pin 6, and special tool 9637, pin III/24.
Display: 0 - 5 ohms
8. Connect ohmmeter to disconnection point, pin 4, and ground.
Display: infinity ohms
9. Connect ohmmeter to disconnection point, pin 6, and ground.
Display: infinity ohms
10. Connect voltmeter to disconnection point, pin 4, and ground.
Switch on the ignition.
Display: 0 V
11. Connect voltmeter to disconnection point, pin 6, and ground.
Switch on the ignition.
Display: 0 V
If battery voltage is indicated for points 10 and 11, check wiring harness for chafing and pinching damage.