Aston Martin diagnostic trouble code
P1397: Battery Voltage Out of Range During KOER/KOEO
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
- V8 Vantage, DB9
- Warning-lamp status
- V8 Vantage: Not stated; DB9: MIL
What Aston Martin code P1397 means
Battery Voltage Out of Range During KOER/KOEO
DB9 preliminary diagnostic manual · section 2-224
Manufacturer fault-analysis procedure
Manual fault definition
P1397 - This code indicates that the system voltage is outside its self-test range.
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
half of the engine.
Primary or Secondary Powertrain Control Module
(PCM). Check that you are working on the correct
half of the engine.
Test sequence and decision path
1. Connect the WDS and confirm that P1397 is
logged. Note which PCM has recorded the fault.
2. Access the underbonnet fusebox. Switch on the
ignition and measure the VPower voltage level at
fuse F4 (Primary PCM) or at F5 (Secondary PCM).
3. If Vpower at either fuse is below 12.5 volts, Complete the charging system check at the end of this
procedure. Return to step 4 of this procedure only
if P1397 is logged again after satisfactory completion of the battery charging check.
If VPower is above 12.5 volts at both fuses, go to
step 4
4. Check the VPower voltage at the battery whilst
cranking the engine. If the voltage drops below
9.6 volts, the battery is defective, replace the battery.
If the voltage at the battery remains above 9.6
volts, Connect the breakout box to the affected
PCM.
5. Monitor the VPower voltage at primary PCM pins
C0635-35 and 36 or at secondary PCM pins
C0638-35 and 36 whilst cranking the engine. If
the voltage drops below 9.6 volts, service the
VBATT and VPower circuits as necessary. Clear
the P1397 code and run a KOER test to ensure
that the problem is resolved.
Battery Charging Check
1. Check the battery voltage at the battery terminals.
If the voltage is above 12.5 volts, switch on the
headlamps for 4 minutes to remove battery surface charge. Measure the battery voltage again, if
above 12.5 volts, go to step 2.
If the voltage is below 12.5 volts, disconnect the
battery and re-measure the open circuit voltage.
If the open circuit voltage is below 12.5 volts,
replace the battery.
If the open circuit voltage is above 12.5 volts, go
to step 2.
2. Reconnect the battery and start the engine.
Switch on the headlamps.
Run the engine at 2000 rpm and measure the battery voltage at the battery terminals.
If the charging voltage reaches 13.8 volts, the
charging system is serviceable.
If below 13.8 volts, the charging system is suspect. Service the charging system as necessary.
Clear the P1397 code and run a KOER test to
ensure that the problem is resolved.
Open the corresponding manual page for wiring diagrams and figures
logged. Note which PCM has recorded the fault.
2. Access the underbonnet fusebox. Switch on the
ignition and measure the VPower voltage level at
fuse F4 (Primary PCM) or at F5 (Secondary PCM).
3. If Vpower at either fuse is below 12.5 volts, Complete the charging system check at the end of this
procedure. Return to step 4 of this procedure only
if P1397 is logged again after satisfactory completion of the battery charging check.
If VPower is above 12.5 volts at both fuses, go to
step 4
4. Check the VPower voltage at the battery whilst
cranking the engine. If the voltage drops below
9.6 volts, the battery is defective, replace the battery.
If the voltage at the battery remains above 9.6
volts, Connect the breakout box to the affected
PCM.
5. Monitor the VPower voltage at primary PCM pins
C0635-35 and 36 or at secondary PCM pins
C0638-35 and 36 whilst cranking the engine. If
the voltage drops below 9.6 volts, service the
VBATT and VPower circuits as necessary. Clear
the P1397 code and run a KOER test to ensure
that the problem is resolved.
Battery Charging Check
1. Check the battery voltage at the battery terminals.
If the voltage is above 12.5 volts, switch on the
headlamps for 4 minutes to remove battery surface charge. Measure the battery voltage again, if
above 12.5 volts, go to step 2.
If the voltage is below 12.5 volts, disconnect the
battery and re-measure the open circuit voltage.
If the open circuit voltage is below 12.5 volts,
replace the battery.
If the open circuit voltage is above 12.5 volts, go
to step 2.
2. Reconnect the battery and start the engine.
Switch on the headlamps.
Run the engine at 2000 rpm and measure the battery voltage at the battery terminals.
If the charging voltage reaches 13.8 volts, the
charging system is serviceable.
If below 13.8 volts, the charging system is suspect. Service the charging system as necessary.
Clear the P1397 code and run a KOER test to
ensure that the problem is resolved.