EGR Valve Diagnosis and Cleaning Procedure using TUNAP 926® on 906, 907 Sprinter with OM642 Diesel Engine
Topic number

LI14.20-N-073867

Version

9

Function group

14.20 - Exhaust gas recirculation

Date

5/9/25

Validity

906, 907 Sprinter with OM642 V6 Diesel Engine

Reason for change

Remedy update

Complaint
Complaint A:
The engine is jolting/bucking between 1700 and 1900 rpm.
Complaint B:
One or more mechanical related fault codes for EGR Valve stored in CDI control unit, with possible Check Engine
Light. Review list of mechanical fault codes in table below.
NOTE: If one or more electrical related fault codes for EGR Valve are also present in CDI, utilize Complaint C. Review
list of electrical fault codes PDF document in attachments.
Complaint C:
One or more electrical related fault codes for EGR Valve stored in CDI control unit, with possible Check Engine Light.
Review list of electrical fault codes PDF document attached.
NOTE: This LI supersedes LI14.20-N-073813, which is no longer valid.

Cause
Cause of Complaint A:
Increased friction between the EGR Valve blade and seat due to soot deposits causing a delay of the EGR Valve
being able to reach the target value of the EGR Valve position controller.
NOTE: This causes the EGR Valve blade and potentially the boost pressure controller to oscillate.
Cause of Complaint B:
Soot deposits between the EGR Valve blade and seat leading to the EGR Valve no longer being able to meet the desired target of the EGR Valve position controller.
Cause of Complaint C:
Internal EGR Valve or other electrical faults related to the EGR Valve function.

Attachments
File

Description

OM642 EGR Valve before 1.jpeg

Bottom of sooted EGR Valve.

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OM642 EGR Valve before 2.jpeg

Side view of sooted EGR Valve.

Remedy

Remedy for Complaint A:
Perform the following steps:
1.
Disable the EGR Valve (Y27/17) by disconnecting the electrical connector.
2.
Perform a test drive to check if the jolting/bucking issue resolves.
3.
If the jolting/bucking is resolved, proceed to Remedy for Complaint B.
4.
If jolting/bucking is still present, proceed with diagnosis to determine the root cause. Consider checking the following, but not limited to:
•
EGR system including the EGR Cooler, EGR Bypass Flap, EGR Temperature Sensor, and pipes for proper operation, excessive sooting and/or clogging, as well as EGR Bypass Flap vacuum element, switchover valve, and
vacuum system.
•
Visually check the leak oil line or T-piece; reference LI07.00-N-059118.
•
Fuel System, including fuel type and quality.
•
Intake system for excessive oil accumulation; If present, check for a worn oil separator or turbocharger.
•
Combustion and compression.
•
Transmission.
•
Evaluate DPF Regeneration History.
•
Plausibility check of the Exhaust Temperature Sensors and Back Pressure Sensor key on engine off check
when the vehicle is cold.
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•

Etc.

Remedy for Complaint B:
Clean the EGR Valve with TUNAP 926® (BQ6670128) by performing the following steps:
NOTE: Prior to performing the cleaning procedure, ensure to run a coverage check of the EGR Valve using the following qualifying damage codes: 4901M, 14315. If no coverage, then performing the procedure is considered customer
pay.
EGR Valve Removal:
1.
Remove the EGR Valve using the appropriate WIS document (document numbers referenced below).
EGR Valve Cleaning:
1.
Attempt to gently turn the EGR Valve blades clockwise to ensure they move. If the blades are seized, the EGR
Valve must be replaced, and therefore, cleaning is not permitted.
2.
Position EGR Valve so open cavity is facing upward. Fill the cavity with cleaner, and then proceed to apply cleaner to the blades from the outside. Additionally, apply cleaner to the outside where additional soot is found.
3.
Allow 15 minutes for the cleaning gel to take effect.
4.
Carefully brush the areas with the supplied cleaner brush or another suitable non-metallic brush with soft bristles; e.g. Kids' size toothbrush and straw cleaning brush (see picture in attachments).
5.
Continue to clean the EGR Valve by turning the EGR Valve blades clockwise to the open position to enable
cleaning the blade seat area. Hold blades in open position by placing a suitable non-metallic holder/wedge in the
hole directly in front of the open cavity (see picture labeled "Blades Open" in attachments).
6.
Rinse the cleaned mechanical areas of the EGR Valve with clear, cold water. Be careful not to get the electrical
connection area of the EGR Valve wet. Furthermore, do not use pressurized water, otherwise, the EGR Valve
can be damaged.
7.
Dry the cleaned areas of the EGR Valve (DO NOT use compressed air).
8.
Check whether soot deposits are still present. If traces of soot deposits are still present, repeat the cleaning process.
NOTES:
1.
2.
3.

Do not lift, pry up, or use excess force on the blades to open during steps 2 and 5 of the cleaning procedure.
If, after a second cleaning, the EGR valve blades do not fully open with light pressure or fail to close under their
spring tension, replace the EGR valve. See the attachment video, EGR Valve binding.
An EGR Valve cleaning video aid is located in the attachments.

Debris Disposal:
•
Refer to the attached MSDS as well as observe local regulations for information on disposal.
EGR Valve Installation and Testing:
1.
Re-install the EGR Valve with a new gasket using the appropriate WIS document (document numbers referenced below).
2.
Following cleaning, initialization of the EGR Valve via XENTRY Diagnosis is NOT required.
3.
Perform a test drive to see if the complaint is resolved.
4.
If the fault persists following the cleaning procedure, proceed to perform further diagnosis to determine the root
cause, beginning with Remedy for Complaint A Step 4.
5.
If no other faults are found following proper diagnosis, it is acceptable to replace the EGR Valve for mechanical
issues.
Remedy for Complaint C:
1.
2.

Diagnose electrical faults.
If the electrical fault is determined to be the EGR Valve, it must be replaced. Cleaning will not be effective for
electrical-related issues of the EGR Valve, and therefore not permitted.

Return Visits:
For repeat concerns following EGR valve cleaning as outlined in this LI, the EGR valve should be replaced. If documentation from a previous repair order or the vehicle’s VMI shows that the EGR valve was cleaned during an earlier
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visit, replacement is permitted. Be sure to include the previous cleaning date and mileage in your warranty claim. There are no restrictions regarding time or mileage since the past cleaning. Please note that EGR valve replacement for
repeat complaints is only allowed if cleaning was performed on a prior visit (i.e., alternate cleaning and replacement:
clean/replace, clean/replace). If the EGR valve has not previously been cleaned, cleaning should be performed before
considering replacement. Please retain all relevant documentation for warranty auditing purposes.
To identify the root cause of increased soot production and accumulation within the EGR system, consider checking
the following items:
• Speak with the client to determine the primary vehicle usage, including driving habits (highway, city, stop-and-go,
short trips) and the amount of idle time the vehicle/engine undergoes.
• Using the wrong oil or exceeding the maintenance interval can lead to increased soot production and accumulation
within the EGR system. If questionable, obtain an oil sample and send it to ALS Tribology for testing and analysis.
• The use of any Diesel fuel exceeding 5% Biodiesel (B20 fuels) or Renewable Diesel fuels can lead to increased soot
production and accumulation within the EGR system. If questionable, obtain a fuel sample and send it to ALS Tribology for testing and analysis.
• Check the EGR system, including the EGR Cooler, EGR Bypass Flap, EGR Temperature Sensor, and pipes for proper operation, excessive sooting, and/or clogging. Also, inspect the EGR Bypass Flap vacuum element, switchover
valve, and vacuum system.
• Visually check the leak oil line or T-piece; reference LI07.00-N-059118.
• Evaluate the fuel system, including fuel type and quality.
• Inspect the intake system for excessive oil accumulation. If present, check for a worn oil separator or turbocharger.
• Low Engine compression, High cylinder loss, or excess oil in the cylinders.
• Evaluate the transmission.
• Review the DPF regeneration history.
• Perform a plausibility check of the Exhaust Temperature Sensors and Back Pressure Sensor with the key on engine
off when the vehicle is cold.
• Consider other potential factors that may contribute to increased soot production.
Ensure to review and follow the following notes:
1.
2.
3.
4.
5.
6.
7.

If the EGR Valve is determined to have a mechanical fault, the EGR Valve must be cleaned first, and thereafter,
test drive the vehicle to see if the issue is resolved before an EGR Valve replacement is to be considered and
accepted as warrantable.
If the EGR Valve requires replacement following cleaning and diagnosis, provided no remedy utilizing steps outlined in Remedy for Complaint A Step 4, state in the write-up that cleaning was performed prior to EGR Valve replacement. This information will be necessary if EGR Valve replacement is claimed under warranty.
If the EGR Valve cleaning is unsuccessful to resolve the issue, the cleaning can still be claimed under warranty
if EGR Valve warranty coverage is available for the vehicle.
If Fault Code P300168 Component 'Exhaust gas recirculation cooler (High pressure)' has a malfunction present
in the CDI Control Module, replace the EGR Cooler due to the inlet being clogged with soot, in addition to cleaning the EGR Valve. Use Damage Code 143159.
If the EGR Valve is damaged while attempting to remove it, the part must be replaced. Ensure to provide an explanation of the damage on RO and provide pictures of the damage to the warranty claim if the repair is warrantable.
The EGR Valve cleaning procedure is NOT valid for OM651 & OM654 equipped Sprinters or Diesel equipped
Passenger Cars.
Do NOT use TUNAP 926® to clean any other EGR system component. This product is only intended to clean
EGR Valves.

Attachments
File

Description

EGR Valve Electrical Fault Codes.pdf

List of EGR Valve Electrical Fault Codes.

OM642 EGR Valve Cleaning Instructional Video using
TUNAP 926®.mp4

OM642 EGR Valve Cleaning Instructional Video using
TUNAP 926.

TUNAP 926® MSDS.PDF

TUNAP 926 MSDS.

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OM642 After Cleaning 1.JPG

Bottom view of cleaned EGR Valve looking at blades.

OM642 EGR After Cleaning 2.JPG

Side view of cleaned EGR Valve.

EGR Valve Cleaner Application.JPG

EGR Valve with cavity filled, and blades covered in cleaner.

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Brushes.JPG

Non-metallic soft brushes to assist in cleaning, and pen
cap used to hold blades open for cleaning.

Blades Open.JPG

Hold blades open to clean using suitable non-metallic holder/wedge placed in the hole directly in front of the open
cavity (i.e. pen cap) to clean blade seats.

EGR Valve Binding.mp4

EGR Valve Binding

WIS-References
Document number

Title

Note

AR14.20-D-7662SG

Remove/install exhaust gas recircula- Engine 642.896/898 in model 906
tion valve

AR14.20-D-7662TSV

Remove/install exhaust gas recircula- Engine 642.899 in model 907
tion valve

Disclaimer
NOTE: The information contained in this document is intended for use by trained, professional technicians with the
knowledge to properly and safely perform diagnosis and repairs on Mercedes-Benz vehicles, using Mercedes-Benz
approved tools and equipment. It informs service technicians about conditions that could occur in certain vehicles and
provides information that could assist in proper vehicle diagnosis, service, or repair. It does not indicate that a defect
is present in any vehicle referenced in this document nor does it imply warranty coverage. DO NOT assume that a
symptom or condition, or a described cause of a symptom or condition, affects any particular vehicle or groups of ve27.05.2025 16:59
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hicles, or that a described repair applies to any particular vehicle or groups of vehicles. There can be multiple causes
resulting in the same or similar symptoms or conditions described in this document, and trained professional service
technicians must use their diagnostic skills to make evaluations on a case-by-case basis. The information contained
in this document does not guarantee warranty coverage nor does it extend the vehicle’s warranty in any way.

Symptoms
Power generation > Engine management > Engine running > Runs rough/shakes
Power generation > Engine management > Indicator lamp > Engine diagnosis > lit
Power generation > Engine management > Function > Malfunction

Parts
Part number

ES1 ES2 Designation

Quantity Note

EPC

A6421422380

Engine

1

OM642 EGR Valve Gasket

X

BQ6670128

Engine

0.5

1 Can of TUNAP 926® BQ6670128
should be able to clean 2 EGR Valves. Claim 0.5 Qty. per Warranty
Claim. For heavily sooted EGR Valves which requires more than 1/2 of
can to clean, claim 1.0 for these special instances.

X

Control unit/fault code
Control unit

Fault text

N3/28 - Motor electronics 'CDI61NFZ' for combustion en- P042FFA - The exhaust gas recirculation positioner (high
gine 'OM642' (CDI) (CR61NFZ)
pressure) is jammed closed. _
P049D00 - The position of the exhaust gas recirculation
positioner (high pressure) is outside the adaptation values. _
P30017E - The position of the exhaust gas recirculation
positioner (high pressure) is outside the adaptation values.
P30017F - The position of the exhaust gas recirculation
positioner (high pressure) is outside the adaptation values. The commanded position cannot be reached.
P300182 - Component 'Exhaust gas recirculation actuator
(high pressure)' has a malfunction. The actuator does not
open.
P300198 - The exhaust gas recirculation positioner (high
pressure) is jammed closed.
P300199 - The exhaust gas recirculation positioner (high
pressure) is jammed open.
CDI6Common Rail Diesel Injection (CR6NFZ)

14A000 - Component 'Y27/17 (Exhaust gas recirculation
positioner)' has an internal fault.
14A100 - Component 'Y27/17 (Exhaust gas recirculation
positioner)' has an internal fault.

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14B700 - The exhaust gas recirculation valve sticks when
closed.
14B800 - EGR valve jams in opened position.
14CF00 - Event:Component 'Y27/17 (Exhaust gas recirculation positioner)' was temporarily sluggish.(Position
control deviation)
148B00 - Exhaust gas recirculation rate is too high.
CDI60Common Rail Diesel Injection (CR60NFZ)

P14A000 - The position of the exhaust gas recirculation
positioner (high pressure) is outside the adaptation values.
P14A100 - The position of the exhaust gas recirculation
positioner (high pressure) is outside the adaptation values.The commanded position cannot be reached.
P14B700 - The exhaust gas recirculation positioner (high
pressure) is jammed closed.
P14B800 - The exhaust gas recirculation positioner (high
pressure) is jammed open.
P148B00 - Component Exhaust gas recirculation positioner has a malfunction.The actuator does not close.

Operation numbers/damage codes
Op. no.

Operation text

Time

Damage
code

Note

4901M01

Use only for EMP 906 Sprinter with
OM642 with active BlueTec Extended Modification Warranty. Total claim not to exceed 2.5 hours
with supporting documentation and
punch times. Also reference LI document number in technician story per
Warranty Policy 10.11.

1431593

Use only for non-EMP 906, 907
Sprinter with OM642 and vehicle
has EGR Valve Warranty Coverage.
Total claim not to exceed 2.5 hours
with supporting documentation and
punch times. Also reference LI document number in technician story per
Warranty Policy 10.11.

070641

Diagnosis of EGR Valve related concerns including CEL, or drivability concern

1.000 H

Punch time must support claimed time.

140000

Clean EGR Valve

0.500 H

Must follow non-time policy with separate and identifiable punch.

147660

Remove and re-install EGR Valve

For time, refer to ASRA.

541011

Quick Test

For time, refer to ASRA.

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