Aston Martin diagnostic trouble code
P0430: Catalyst System Efï¬ciency Below Threshold (Bank 2)
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
- Emissions and EVAP
- Manual coverage
- V8 Vantage, DB9
- Warning-lamp status
- V8 Vantage: MIL; DB9: MIL
What Aston Martin code P0430 means
Catalyst System Efï¬ciency Below Threshold (Bank 2)
DB9 preliminary diagnostic manual · section 2-88
Manufacturer fault-analysis procedure
Manual fault definition
P0430 - Indicates that cylinder 4-6 catalyst system
efficiency is below the acceptable threshold.
efficiency is below the acceptable threshold.
Cautions and notes
NOTE: Fuel pressure outside specification can cause
incorrect fuel air mixture leading to higher than normal
catalyst temperatures.
Run the engine at idle. Record the fuel pressure.
Increase engine speed to 2500 rpm and maintain
for one minute. Record the fuel pressure.
The nominal fuel pressure specification is 40 psi
above manifold pressure.
If fuel pressure is in specification, go on to step 7.
If fuel pressure is out of specification, service the
fuel system as necessary. Reset the PCM and run
a KOER test to ensure that the problem is
resolved.
NOTE: The vacuum gauge reading may be normal when
the engine is first started and idled. However, excessive
restriction in the exhaust system will cause the vacuum
to diminish even when the engine is idling.
Note the initial gauge reading and any change in
the reading during the initial period at idle speed.
Steadily increase engine speed to 2000 rpm, then
allow it to slowly decrease back to idle speed.
The manifold vacuum must rise to at least 16
inches Hg with the engine at 2000 rpm.
If a vacuum of less than 16 inches Hg at 2000
rpm is observed, remove the exhaust system and
check for restrictions or blockage.
If the manifold vacuum met the basic specification, the P0420/P0430 codes are caused by poor
catalyst performance, change the catalytic convertors and run the drive cycle to ensure that the
problem is resolved.
incorrect fuel air mixture leading to higher than normal
catalyst temperatures.
Run the engine at idle. Record the fuel pressure.
Increase engine speed to 2500 rpm and maintain
for one minute. Record the fuel pressure.
The nominal fuel pressure specification is 40 psi
above manifold pressure.
If fuel pressure is in specification, go on to step 7.
If fuel pressure is out of specification, service the
fuel system as necessary. Reset the PCM and run
a KOER test to ensure that the problem is
resolved.
NOTE: The vacuum gauge reading may be normal when
the engine is first started and idled. However, excessive
restriction in the exhaust system will cause the vacuum
to diminish even when the engine is idling.
Note the initial gauge reading and any change in
the reading during the initial period at idle speed.
Steadily increase engine speed to 2000 rpm, then
allow it to slowly decrease back to idle speed.
The manifold vacuum must rise to at least 16
inches Hg with the engine at 2000 rpm.
If a vacuum of less than 16 inches Hg at 2000
rpm is observed, remove the exhaust system and
check for restrictions or blockage.
If the manifold vacuum met the basic specification, the P0420/P0430 codes are caused by poor
catalyst performance, change the catalytic convertors and run the drive cycle to ensure that the
problem is resolved.
Test sequence and decision path
1. Ensure that the customer has not refuelled the vehicle with leaded fuel
2. Ensure that the customer has not experienced high
oil consumption.
3. Internal deterioration of a catalytic convertor is
usually caused by abnormal engine operation
upstream of the catalyst. Events which may produce higher than normal temperatures, e.g. misfiring, are particularly suspect.
1. Connect the WDS and note all logged DTCs. If
any misfire DTCs P0300 - P0306 are recorded,
analyse the misfire problem first.
2. If any HO2S DTCs P0133, P0135, P0141, P0155
or P0161 are recorded, analyse these problems,
then return to this procedure.
3. If any ECT sensor DTCs are recorded P0116,
P0117, P0118, P0119 or P1116, analyse these
problems, then return to this procedure.
4. If any other DTCs are recorded, analyse these
codes, then return to this procedure.
5. Check the wiring of each rear heated oxygen sensor. If any wiring error is found, correct it, then
reset the PCM memory and rerun the KOER Test
to check that the problem is resolved. If no wiring
errors are found, go to step 6.
6. Whilst running the engine, use datalogger to
compare the upstream and downstream oxygen
sensor signals.
If the signals are significantly different, indicating
a correctly working catalyst, go to step 6.
If the upstream and downstream signals on either
bank are identical, the catalyst on that bank is
defective and must be replaced. Investigate for
possible causes before running the engine on the
new catalyst.
7. Use datalogger to monitor the fuel pressure in
both fuel rails.
8. Check for leaks or damage in the exhaust system.
Examine all flanges for security and leaks. Examine all components for splits or serious corrosion.
Examine all supports for security to avoid any
flexing of the system under road shock. Check for
damage which could cause restrictions.
If any defects are identified, repair or replace
components as necessary and retest the vehicle to
check for complete resolution of the problem. If
no defects are found, go to step 8.
9. Check the inlet manifold vacuum:
Attach a vacuum gauge to the inlet manifold.
Start the engine and allow it to run at idle speed
whilst observing the vacuum gauge.
Open the corresponding manual page for wiring diagrams and figures
2. Ensure that the customer has not experienced high
oil consumption.
3. Internal deterioration of a catalytic convertor is
usually caused by abnormal engine operation
upstream of the catalyst. Events which may produce higher than normal temperatures, e.g. misfiring, are particularly suspect.
1. Connect the WDS and note all logged DTCs. If
any misfire DTCs P0300 - P0306 are recorded,
analyse the misfire problem first.
2. If any HO2S DTCs P0133, P0135, P0141, P0155
or P0161 are recorded, analyse these problems,
then return to this procedure.
3. If any ECT sensor DTCs are recorded P0116,
P0117, P0118, P0119 or P1116, analyse these
problems, then return to this procedure.
4. If any other DTCs are recorded, analyse these
codes, then return to this procedure.
5. Check the wiring of each rear heated oxygen sensor. If any wiring error is found, correct it, then
reset the PCM memory and rerun the KOER Test
to check that the problem is resolved. If no wiring
errors are found, go to step 6.
6. Whilst running the engine, use datalogger to
compare the upstream and downstream oxygen
sensor signals.
If the signals are significantly different, indicating
a correctly working catalyst, go to step 6.
If the upstream and downstream signals on either
bank are identical, the catalyst on that bank is
defective and must be replaced. Investigate for
possible causes before running the engine on the
new catalyst.
7. Use datalogger to monitor the fuel pressure in
both fuel rails.
8. Check for leaks or damage in the exhaust system.
Examine all flanges for security and leaks. Examine all components for splits or serious corrosion.
Examine all supports for security to avoid any
flexing of the system under road shock. Check for
damage which could cause restrictions.
If any defects are identified, repair or replace
components as necessary and retest the vehicle to
check for complete resolution of the problem. If
no defects are found, go to step 8.
9. Check the inlet manifold vacuum:
Attach a vacuum gauge to the inlet manifold.
Start the engine and allow it to run at idle speed
whilst observing the vacuum gauge.
Supporting owner context
What owners have reported
Owner discussions include catalyst-efficiency codes after aftermarket catalyst changes. Check the exhaust, sensors and calibration context; a forum workaround should not be treated as a repair.
This is supporting owner-reported context, not a replacement for the manufacturer procedure or a diagnosis of every vehicle.
Read the related owner discussion