Aston Martin diagnostic trouble code
P2121: Throttle/Pedal Position Sensor/Switch D Circuit Range/Performance
Use this reference to understand the recorded condition, confirm the available V8 Vantage or DB9 manual coverage, and follow the documented diagnostic checks before replacing parts.
- Code family
- Powertrain
- Vehicle system
- Fuel and air
- Manual coverage
- V8 Vantage, DB9
- Warning-lamp status
- V8 Vantage: Not stated; DB9: MIL
What Aston Martin code P2121 means
Throttle/Pedal Position Sensor/Switch D Circuit Range/Performance
DB9 preliminary diagnostic manual · section 2-300
Manufacturer fault-analysis procedure
Manual fault definition
P2121 - PPS1 Range/Performance
P2122 - PPS1 circuit low input
P2123 - PPS1 high input
P2124 - PPS1 circuit intermittent
P2126 - PPS2 Range/Performance
P2127 - PPS2 circuit low input
P2128 - PPS2 high input
P2129 - PPS2 circuit intermittent
P2122 - PPS1 circuit low input
P2123 - PPS1 high input
P2124 - PPS1 circuit intermittent
P2126 - PPS2 Range/Performance
P2127 - PPS2 circuit low input
P2128 - PPS2 high input
P2129 - PPS2 circuit intermittent
Test sequence and decision path
1. Connect the WDS and record all logged DTCs.
Ensure that a code in the range P2121 - P2129 is
logged and note which PCM has recorded the
fault.
2. Set datalogger to monitor the pedal position sensor votages at the affected PCM.
3. Check the voltage level of the APP (accelerator
pedal position) signals at the following points referenced to chassis ground.
Primary PCM - APP1 - C0635-5
Primary PCM - APP2 - C0635-17
Secondary PCM - APP1 - C0638-5
Secondary PCM - APP2 - C0638-17
APP1 should read 4v at idle and 0.5v at full
throttle
APP2 should read 1.0v at idle and 3.5v at full
throttle.
If the signals remain at 0v, go to step 5.
If the signals respond normally to throttle
movement, go to step 4.
If any signal does not change or fails to change
over the full range, service the circuit as
necessary. Clear the fault code and run a brief
road test to ensure that the problem is resolved
4. Repeat the voltage check from step 3 but use the
signal return lines as a reference for each signal.
Primary PCM - APP1 - C0635-5 ref APP1 rtn
C0635-6
Primary PCM - APP2 - C0635-17 ref APP2 rtn
C0635-18
Secondary PCM - APP1 - C0638-5 ref APP1 rtn
C0638-6
Secondary PCM - APP2 - C0638-17 ref APP2 rtn
C0638-18
If any signal does not respond correctly to throttle
pedal movements, service the signal return line as
necessary. Clear the fault code and run a brief
road test to ensure that the problem is resolved.
5. Check the BVREF supplies at the following pints:
Primary PCM
APP1 BVREF C0635-4 to C0635-6
APP2 BVREF C0635-16 to C0635-18
Secondary PCM
APP1 BVREF C0638-4 to C0638-6
APP2 BVREF C0638-16 to C0638-18
If any voltage is less than 5 volts, service the
circuit as necessary, checking particularly for
partial short circuits to ground. Clear the fault
code and run a brief road test to ensure that the
problem is resolved.
If no open circuit is detected, clear the P2101/2/3
code and conduct an extended road test to ensure
that the throttle control circuit is totally serviceable.
Open the corresponding manual page for wiring diagrams and figures
Ensure that a code in the range P2121 - P2129 is
logged and note which PCM has recorded the
fault.
2. Set datalogger to monitor the pedal position sensor votages at the affected PCM.
3. Check the voltage level of the APP (accelerator
pedal position) signals at the following points referenced to chassis ground.
Primary PCM - APP1 - C0635-5
Primary PCM - APP2 - C0635-17
Secondary PCM - APP1 - C0638-5
Secondary PCM - APP2 - C0638-17
APP1 should read 4v at idle and 0.5v at full
throttle
APP2 should read 1.0v at idle and 3.5v at full
throttle.
If the signals remain at 0v, go to step 5.
If the signals respond normally to throttle
movement, go to step 4.
If any signal does not change or fails to change
over the full range, service the circuit as
necessary. Clear the fault code and run a brief
road test to ensure that the problem is resolved
4. Repeat the voltage check from step 3 but use the
signal return lines as a reference for each signal.
Primary PCM - APP1 - C0635-5 ref APP1 rtn
C0635-6
Primary PCM - APP2 - C0635-17 ref APP2 rtn
C0635-18
Secondary PCM - APP1 - C0638-5 ref APP1 rtn
C0638-6
Secondary PCM - APP2 - C0638-17 ref APP2 rtn
C0638-18
If any signal does not respond correctly to throttle
pedal movements, service the signal return line as
necessary. Clear the fault code and run a brief
road test to ensure that the problem is resolved.
5. Check the BVREF supplies at the following pints:
Primary PCM
APP1 BVREF C0635-4 to C0635-6
APP2 BVREF C0635-16 to C0635-18
Secondary PCM
APP1 BVREF C0638-4 to C0638-6
APP2 BVREF C0638-16 to C0638-18
If any voltage is less than 5 volts, service the
circuit as necessary, checking particularly for
partial short circuits to ground. Clear the fault
code and run a brief road test to ensure that the
problem is resolved.
If no open circuit is detected, clear the P2101/2/3
code and conduct an extended road test to ensure
that the throttle control circuit is totally serviceable.