Service

Technical Information

246/24 ENU

1001

1

Combustion Misfiring / Irregular Engine Running during Catalytic Converter Heating Phase and Yellow
Malfunction Indicator Light (MIL) Active: Clean the Injector Valves (246/24)
Vehicle Type:

Panamera 4 E-Hybrid (971) / Panamera 4S E-Hybrid (971)

Model Year:

As of 2021 up to 2024

Equipment:

Hybrid drive system PHEV (M-No. 0K3)

Concerns:

Combustion engine

Cause:

Customers complain about irregular engine running during the catalytic converter heating phase and the
yellow malfunction indicator light (MIL) on the instrument cluster lighting up.
Combustion misfiring can occur during the catalytic converter heating phase due to coking of the fuel
injectors.
Information
The catalytic converter is in the heating phase at:

Action:

•

Cold start of the combustion engine

•

Restarting the combustion engine after a pure electric drive

Limit fault pattern and, if necessary, clean the fuel injectors by adding the fuel additive “Keropur”.

Required tools and materials
Tools:

•
•

P90999 - PIWIS Tester 4
Battery charger with a current rating of at least 90 A and a current and voltage-controlled charge map
for lithium starter batteries, e.g. VAS5908 battery charger 90 A. For further information about the
battery chargers to be used, see the corresponding Workshop Manual. ⇒ Workshop Manual '270689
Charging vehicle electrical system battery'

Material:

Required materials as needed (usually already available in the Porsche Center)
Part No.

Designation

Quantity

00004320902

⇒ Fuel additive “Keropur” (100 ml/ 3.38 fl oz
container)

2 cans

Limit fault pattern and clean fuel injectors if necessary
Work Procedure: 1

Connect and switch on the battery charger.
⇒ Workshop Manual '270689 Charge vehicle electrical system battery'

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Service

Technical Information

ENU 246/24

1001
2

Connect P90999 - PIWIS Tester 4 to the vehicle. Switch on ignition. Start the diagnostic application.

3

Create and evaluate Vehicle Analysis Log (VAL).
Assessment
•

Action

Fault “P030000 - Combustion misfiring detected” is The fuel injectors are contaminated.
present in the fault memory of the DME control unit Go to ⇒ 4.
⇒ DME control unit fault memory entry

DME control unit fault memory entry
•

In addition, the measured values show the following
engine torque when the fault occurs: between 80 90 Nm (59 - 66.4 ftlb.) ⇒ Engine torque measured
values

Engine torque measured values
Fault “P030000 - combustion misfiring detected” is not
present in the fault memory of the DME control unit.

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The irregular engine running cannot be
solved by this SY.
Continue with troubleshooting.

Service

Technical Information
4

246/24 ENU

1001

1

Pour in two cans of “Keropur” to the fuel tank.
⇒ Fuel additive "Keropur".

Information
The following prerequisites must be met before carrying out
the action:
•

The cause for the ignition failures was narrowed down
to the fuel injectors (review of the torque requirement
in the VAL)

•

The vehicle fuel tank is at least 3/4 full with fuel

Fuel additive "Keropur"

Information
The one-time use of Keropur ensures complete cleaning of the injectors.
Regular use can cause damage to the fuel system. Frequent engine cold starts, low-engine load driving and
short engine running times, among other things can proliferate coking on the injectors.
If another complaint about the combustion misfiring is made and the injectors are not coked up, proceed as
given in the guided troubleshooting.
5

Delete existing faults in the fault memory of the DME control unit.

6

End the diagnostic application. Switch off ignition. Disconnect P90999 - PIWIS Tester 4 from the
vehicle.

7
8

Switch off and disconnect the battery charger.

⇒ Workshop Manual '270689 Charge vehicle electrical system battery'
Hand the vehicle over to the customer.

Information
The fuel injectors are cleaned separately. No special driving manoeuvres or driving profiles are required.

PCSS encryption
Labor position:
APOS

Labor operation

24403040

Clean the injector valves

I No.

PCSS encryption:
Location (FES5)

1001H

Hybrid engine

Damage type (SA4)

1117

Misfiring, jerking

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Service
1001

Technical Information

ENU 246/24

Important Notice: Technical Bulletins issued by Porsche Cars North America, Inc. are intended only for use by professional automotive technicians who have attended Porsche service training courses. They are
written to inform those technicians of conditions that may occur on some Porsche vehicles, or to provide information that could assist in the proper servicing of a vehicle. Porsche special tools may be necessary in
order to perform certain operations identified in these bulletins. Use of tools and procedures other than those Porsche recommends in these bulletins may be detrimental to the safe operation of your vehicle, and
may endanger the people working on it. Properly trained Porsche technicians have the equipment, tools, safety instructions, and know-how to do the job properly and safely. Part numbers listed in these bulletins
are for reference only. The work procedures updated electronically in the Porsche PIWIS diagnostic and testing device take precedence and, in the event of a discrepancy, the work procedures in the PIWIS Tester
are the ones that must be followed.

© 2025 Porsche Cars North America, Inc.

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