Aston Martin diagnostic trouble code
P0172: System Too Rich (Bank 1)
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
- Other vehicle system
- Manual coverage
- V8 Vantage, DB9
- Warning-lamp status
- V8 Vantage: MIL; DB9: MIL
What Aston Martin code P0172 means
System Too Rich (Bank 1)
DB9 preliminary diagnostic manual · section 2-48
Manufacturer fault-analysis procedure
Manual fault definition
P0172 - HO2S1-1 Fuel/air ratio too rich. Adaptive
fuel correction at the limit.
P0175 - HO2S2-1 Fuel/air ratio too rich. Adaptive
fuel correction at the limit.
fuel correction at the limit.
P0175 - HO2S2-1 Fuel/air ratio too rich. Adaptive
fuel correction at the limit.
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. Verify that the vehicle did not run out of fuel
before the Check Engine light came on.
If a No Fuel condition has been present, connect
the WDS or scan tool and clear the P0172/P0175
code. Perform the KOER test sequence to check
that the fuel adaption is now functioning correctly.
If the vehicle has not recently run out of fuel, analyse the problem using the following procedure.
2. Carry out a thorough visual inspection of the
vehicle, concentrating on the following possible
causes of the rich mixture:
Fuel System
Leaking fuel injectors
Leaking fuel pressure regulator
High fuel pressure
Fuel Vapour Purge System
Damaged/disconnected HO2S circuits
Induction System
Air leaks after the air flow meter
Vacuum leaks
Restricted air inlet
Positive Crankcase Ventilation system
Base Engine
Oil overfill
Cam timing
Compression pressure
Ignition System
Coil secondary windings
Ignition HT leads
Spark plugs
Repair any problems identified in the visual
inspection, clear the P0172/P0175 fault codes
and repeat the KOER Test.
If the P0172/P0175 code is detected proceed as
follows.
3. Connect the WDS or scan tool. Perform the KOER
test sequence.
If any adaptive fuel codes are detected, go to step
4. For other codes, go to the appropriate procedure in this section of the fault analysis manual.
4. Check the fuel pressure as follows:
Connect the WDS and set to monitor the fuel
pressure sensor output from both fuel rails.
Start the engine and run at idle speed. Record the
fuel pressure. Increase the engine speed to 2500
rpm and maintain for 1 minute. Record the fuel
pressure.
The fuel system must be capable of maintaining
at least 40 psi above manifold pressure.
5. Check the fuel system ability to hold fuel pressure.
Cycle the ignition key on and off several times.
Check for external fuel leaks (repair as necessary)
Verify that with the ignition off, fuel pressure stays
within 5 psi of the highest reading for 1 minute. If
excessive pressure loss is detected, service or
repair the fuel system to correct the problem.
Figure 3. Fuel Injector Circuits
BU,0.5
BY,0.5
BK,0.5
BW,0.5
BS,0.5
BR,0.5
KB,0.5
WB,0.5
RB,0.5
SB,0.5
UB,0.5
KB,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
Conn-ECU B (E-Engine)
Injector 12
Underbonnet Fusebox
Module
Central Electronic
Sheet 61
Sheet 61
C2409-1
DIODE 4
RELAY 3
DIODE 5
RELAY 5
F54
10.0 Amps
F13
20.0 Amps
F9
20.0 Amps
12 Ohms
12 Ohms
12 Ohms
12 Ohms
12 Ohms
12 Ohms
Injector 8
Injector 7
Injector 9
Injector 11
Injector 10
12 Ohms
12 Ohms
12 Ohms
12 Ohms
12 Ohms
12 Ohms
Injector 1
Injector 2
Injector 3
Injector 4
Injector 5
Injector 6
Conn-ECU A (E-Engine)
C0584-39
IGN. OUT
C0574-6 GND
C2608-1 VBATT
C0579-8 VIGN
SPL5-VIGN/EN
C0578-2
C0577-6
SPL2-VIGN/EN
C0529-2
C0528-2
C2456-2
C2459-2
C2458-2
C2457-2
C0529-1
C0528-1
C2456-1
C2459-1
C2458-1
C2457-1
C0522-2
C0523-2
C0524-2
C0525-2
C0526-2
C0527-2
C0522-1
C0523-1
C0524-1
C0525-1
C0526-1
C0527-1
C2464-2G INJ7
C2464-8G INJ11
C2464-9G INJ8
C2464-3G INJ12
C2464-4G INJ10
C2464-5G INJ9
C0636-2G INJ1
C0636-8G INJ5
C0636-5G INJ3
C0636-9G INJ2
C0636-4G INJ4
C0636-3G INJ6
See Power Distribution
6. Key off. Disconnect the fuel injector connectors.
Check the resistance of the fuel injectors.
Each resistance should be in the range 11 - 18
Ω
If all injector resistance values are in range, go to
step 7.
If any injector resistance is out of range, replace
the injector.
Reconnect all injectors. Clear the P0172/P0175
codes and run a KOER test to ensure that the
problem is resolved.
7. Check for codes P0201 to P0206 (injector faults)
and analyse these codes if present. Return to step
9 of this procedure if P0171 is logged again after
clearing the P0201 - P0206 codes.
8. Flow test the injectors:
Use a Rotunda Injector Tester or equivalent to
flow test the injectors according to the manufacturers instructions.
If any injector flow rate is not within specification, replace the defective injector. Rerun the
KOER Test.
If the injector flow rates are all within specification, the problem is not fuel related.
9. Check the cylinder compression pressures using
the service manual procedure.
If any compression pressure is low, repair the
engine as necessary.
If the compression pressures are in specification,
carry out further analysis as for DTC P1131 to
check the heated oxygen sensors and circuits.
Open the corresponding manual page for wiring diagrams and figures
before the Check Engine light came on.
If a No Fuel condition has been present, connect
the WDS or scan tool and clear the P0172/P0175
code. Perform the KOER test sequence to check
that the fuel adaption is now functioning correctly.
If the vehicle has not recently run out of fuel, analyse the problem using the following procedure.
2. Carry out a thorough visual inspection of the
vehicle, concentrating on the following possible
causes of the rich mixture:
Fuel System
Leaking fuel injectors
Leaking fuel pressure regulator
High fuel pressure
Fuel Vapour Purge System
Damaged/disconnected HO2S circuits
Induction System
Air leaks after the air flow meter
Vacuum leaks
Restricted air inlet
Positive Crankcase Ventilation system
Base Engine
Oil overfill
Cam timing
Compression pressure
Ignition System
Coil secondary windings
Ignition HT leads
Spark plugs
Repair any problems identified in the visual
inspection, clear the P0172/P0175 fault codes
and repeat the KOER Test.
If the P0172/P0175 code is detected proceed as
follows.
3. Connect the WDS or scan tool. Perform the KOER
test sequence.
If any adaptive fuel codes are detected, go to step
4. For other codes, go to the appropriate procedure in this section of the fault analysis manual.
4. Check the fuel pressure as follows:
Connect the WDS and set to monitor the fuel
pressure sensor output from both fuel rails.
Start the engine and run at idle speed. Record the
fuel pressure. Increase the engine speed to 2500
rpm and maintain for 1 minute. Record the fuel
pressure.
The fuel system must be capable of maintaining
at least 40 psi above manifold pressure.
5. Check the fuel system ability to hold fuel pressure.
Cycle the ignition key on and off several times.
Check for external fuel leaks (repair as necessary)
Verify that with the ignition off, fuel pressure stays
within 5 psi of the highest reading for 1 minute. If
excessive pressure loss is detected, service or
repair the fuel system to correct the problem.
Figure 3. Fuel Injector Circuits
BU,0.5
BY,0.5
BK,0.5
BW,0.5
BS,0.5
BR,0.5
KB,0.5
WB,0.5
RB,0.5
SB,0.5
UB,0.5
KB,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
NY,0.5
Conn-ECU B (E-Engine)
Injector 12
Underbonnet Fusebox
Module
Central Electronic
Sheet 61
Sheet 61
C2409-1
DIODE 4
RELAY 3
DIODE 5
RELAY 5
F54
10.0 Amps
F13
20.0 Amps
F9
20.0 Amps
12 Ohms
12 Ohms
12 Ohms
12 Ohms
12 Ohms
12 Ohms
Injector 8
Injector 7
Injector 9
Injector 11
Injector 10
12 Ohms
12 Ohms
12 Ohms
12 Ohms
12 Ohms
12 Ohms
Injector 1
Injector 2
Injector 3
Injector 4
Injector 5
Injector 6
Conn-ECU A (E-Engine)
C0584-39
IGN. OUT
C0574-6 GND
C2608-1 VBATT
C0579-8 VIGN
SPL5-VIGN/EN
C0578-2
C0577-6
SPL2-VIGN/EN
C0529-2
C0528-2
C2456-2
C2459-2
C2458-2
C2457-2
C0529-1
C0528-1
C2456-1
C2459-1
C2458-1
C2457-1
C0522-2
C0523-2
C0524-2
C0525-2
C0526-2
C0527-2
C0522-1
C0523-1
C0524-1
C0525-1
C0526-1
C0527-1
C2464-2G INJ7
C2464-8G INJ11
C2464-9G INJ8
C2464-3G INJ12
C2464-4G INJ10
C2464-5G INJ9
C0636-2G INJ1
C0636-8G INJ5
C0636-5G INJ3
C0636-9G INJ2
C0636-4G INJ4
C0636-3G INJ6
See Power Distribution
6. Key off. Disconnect the fuel injector connectors.
Check the resistance of the fuel injectors.
Each resistance should be in the range 11 - 18
Ω
If all injector resistance values are in range, go to
step 7.
If any injector resistance is out of range, replace
the injector.
Reconnect all injectors. Clear the P0172/P0175
codes and run a KOER test to ensure that the
problem is resolved.
7. Check for codes P0201 to P0206 (injector faults)
and analyse these codes if present. Return to step
9 of this procedure if P0171 is logged again after
clearing the P0201 - P0206 codes.
8. Flow test the injectors:
Use a Rotunda Injector Tester or equivalent to
flow test the injectors according to the manufacturers instructions.
If any injector flow rate is not within specification, replace the defective injector. Rerun the
KOER Test.
If the injector flow rates are all within specification, the problem is not fuel related.
9. Check the cylinder compression pressures using
the service manual procedure.
If any compression pressure is low, repair the
engine as necessary.
If the compression pressures are in specification,
carry out further analysis as for DTC P1131 to
check the heated oxygen sensors and circuits.