Aston Martin diagnostic trouble code
P2138: Throttle/Pedal Position Sensor/Switch D / E Voltage Correlation
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 P2138 means
Throttle/Pedal Position Sensor/Switch D / E Voltage Correlation
DB9 preliminary diagnostic manual · section 2-304
Manufacturer fault-analysis procedure
Manual fault definition
P2138 Throttle Pedal Position Sensor PPS1 v PPS2
Voltage Correlation.
P2139 Throttle Pedal Position Sensor PPS1 v PPS2
Voltage Correlation.
Voltage Correlation.
P2139 Throttle Pedal Position Sensor PPS1 v PPS2
Voltage Correlation.
Test sequence and decision path
1. Connect the WDS and record all logged DTCs.
Ensure that code P2138 or P2139 is logged and
note which PCM has recorded the fault.
2. Fit the breakout box to the affected PCM.
3. Ignition on. Check that the BVREF signal to each
throttle potentiometer is within the range 4.5 -
5.5 volts measured at the following pins reference
to chassis ground:
Primary PCM C0635-4 and C0635-16
Secondary PCM C0638-4 and C0638-16
If BVREF is in specification, go to step 4.
If any BVREF signal is out of range, troubleshoot
the power supplies to the PCMs. Clear the P2138
or P2139 code and run a KOER test to ensure that
the problem is resolved.
4. Using datalogger, measure each Pedal Position
signal at the following points. The signals should
be x volts throttle closed, rising to y volts throttle
open:
Primary PCM
APP1 C0635-5 to C0635-6
APP2 C0635-17 to C0635-18
Secondary PCM
APP1 C0638-5 to C0638-6
APP2 C0638-17 to C0638-18
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 any signal is out of range, service the pedal
sensors as necessary. Clear the fault code and
retest to ensure that the problem is resolved.
Open the corresponding manual page for wiring diagrams and figures
Ensure that code P2138 or P2139 is logged and
note which PCM has recorded the fault.
2. Fit the breakout box to the affected PCM.
3. Ignition on. Check that the BVREF signal to each
throttle potentiometer is within the range 4.5 -
5.5 volts measured at the following pins reference
to chassis ground:
Primary PCM C0635-4 and C0635-16
Secondary PCM C0638-4 and C0638-16
If BVREF is in specification, go to step 4.
If any BVREF signal is out of range, troubleshoot
the power supplies to the PCMs. Clear the P2138
or P2139 code and run a KOER test to ensure that
the problem is resolved.
4. Using datalogger, measure each Pedal Position
signal at the following points. The signals should
be x volts throttle closed, rising to y volts throttle
open:
Primary PCM
APP1 C0635-5 to C0635-6
APP2 C0635-17 to C0635-18
Secondary PCM
APP1 C0638-5 to C0638-6
APP2 C0638-17 to C0638-18
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 any signal is out of range, service the pedal
sensors as necessary. Clear the fault code and
retest to ensure that the problem is resolved.