Aston Martin diagnostic trouble code
P0725: Engine Speed Input Circuit Plausibility Error
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
- Electrical and control modules
- Manual coverage
- DB9
- Warning-lamp status
- DB9: MIL
What Aston Martin code P0725 means
Engine Speed Input Circuit Plausibility Error
DB9 preliminary diagnostic manual · section 2-172
Manufacturer fault-analysis procedure
Cautions and notes
CAUTION: This code may be generated in the
Primary or Secondary Powertrain Control Module
(PCM). Check that you are working on the correct
PCM.
Primary or Secondary Powertrain Control Module
(PCM). Check that you are working on the correct
PCM.
Test sequence and decision path
1. Connect the WDS and confirm that P0725 is
logged.
2. Set the WDS datalogger to log engine speed (‘N’).
for both engine banks. Start the engine and perform a brief road test whilst logging the engine
speed signals.
3. Stop the road test and review the datalogger
results.
If the engine speed is not correctly logged in the
primary PCM, go to step 4.
If the engine speed is correctly logged in the primary PCM, check continuity of the CAN bus to
the TCM in the gearbox.
If a CAN continuity fault is identified, service the
wiring as necessary. Clear the P0725 code and
run a brief road test to ensure that the problem is
resolved.
If continuity is good, replace the TCM, clear the
P0725 codes and run a brief road test to ensure
that the problem is resolved
4. With the engine running, compare the crank
position sensor signals for both engine banks.
If the signals are mismatched, go to step 5.
If the signals are matched, consult Aston Martin
Technical Support.
5. Swap the crank sensors bank to bank and repeat
the test. If the fault changes sides, replace the suspect sensor. Clear the P0725 code and run a
KOER test to ensure that the problem is resolved.
If the fault does not swap sides, service the wiring
from C0168-2 at the sensor to C0636-34 at the
PCM and from Co168-1 at the sensor to C0636-
45 at the PCM. Run a brief road test to confirm
that the problem is resolved.
If the P0725 code is logged again, consult Aston
Martin Technical Support.
Open the corresponding manual page for wiring diagrams and figures
logged.
2. Set the WDS datalogger to log engine speed (‘N’).
for both engine banks. Start the engine and perform a brief road test whilst logging the engine
speed signals.
3. Stop the road test and review the datalogger
results.
If the engine speed is not correctly logged in the
primary PCM, go to step 4.
If the engine speed is correctly logged in the primary PCM, check continuity of the CAN bus to
the TCM in the gearbox.
If a CAN continuity fault is identified, service the
wiring as necessary. Clear the P0725 code and
run a brief road test to ensure that the problem is
resolved.
If continuity is good, replace the TCM, clear the
P0725 codes and run a brief road test to ensure
that the problem is resolved
4. With the engine running, compare the crank
position sensor signals for both engine banks.
If the signals are mismatched, go to step 5.
If the signals are matched, consult Aston Martin
Technical Support.
5. Swap the crank sensors bank to bank and repeat
the test. If the fault changes sides, replace the suspect sensor. Clear the P0725 code and run a
KOER test to ensure that the problem is resolved.
If the fault does not swap sides, service the wiring
from C0168-2 at the sensor to C0636-34 at the
PCM and from Co168-1 at the sensor to C0636-
45 at the PCM. Run a brief road test to confirm
that the problem is resolved.
If the P0725 code is logged again, consult Aston
Martin Technical Support.