Aston Martin diagnostic trouble code

P0620: Alternator Control Circuit

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 P0620 means

Alternator Control Circuit

DB9 preliminary diagnostic manual · section 2-148

Manufacturer fault-analysis procedure

Manual fault definition

P0620 - Generator Control Circuit
P0622 - Alternator field terminal circuit

Cautions and notes

CAUTION: This code should be generated only in
the 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 P0620 or
P0622 is logged.

2. For P0620, check continuity of the ALTMON signal line from secondary PCM connector C0637-
38 to C0226-1 on the alternator.
Also check for any short circuit to power or
ground on this line.
Service the circuit as necessary. Clear the P0620
code. Run the engine and check that the problem
is resolved.

3. For P0622, check that +12volts is present on
alternator connector C0226-3 (BATT SENSE). If
+12 volts is not present, service the battery sense
circuit from underbonnet fusebox F30 to the
alternator. Clear the P0622 code. Run the engine
and check that the problem is resolved.
Open the corresponding manual page for wiring diagrams and figures