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CANADA, UNITED STATES Document ID: IK1201516

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ISIS, FleetISIS, NotSIR

Revision:

2

Major System:

ENGINE

Created:

6/2/2025

Current Language: English

Last Modified: 12/17/2025

Other Languages: NONE

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Brandon Heisler

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Title : 2021 A26 (A26B) - Intermittent Shutdown
Applies To : 2021 A26 ESN 4600000 - 4699999

CHANGE LOG
Please refer to the change log text box below for recent changes to this article:
12/17/2025 - Removal of IKNOW article reference on step 5, changed to push to 132 GUIDE session
08/06/2025 - IMP isolation kit parts information and installation instructions added. Indication to open a tech service case removed from final step.
06/11/2025 - Initial Article Release

**PLEASE COMPLETE ALL PUBLISHED DIAGNOSTICS BEFORE PERFORMING THESE STEPS.**
The diagnostics within this document are supplemental diagnostic steps only. This article is intended to be followed when all published diagnostics have been exhausted and there is no
current repair direction or solution. Failure to follow published diagnostics can result in improper diagnostics being performed, and may also lead to extended downtime for the customer.
Technical Service Support teams have created this article for a short-term solution while pending published diagnostics are enhanced and updated. Once those diagnostics have been
updated, this article will be retired. Always reference published manuals, FCAPs, and GUIDE sessions before performing the steps below.

DESCRIPTION
This document will guide the user through diagnosing an intermittent shutdown complaint on a 2021 A26 (A26B), whether the vehicle is coming to a stop or
sitting at idle.

SYMPTOM(s)
Diagnostic Trouble Code(s) & Dashboard Indicator Light(s):
There should be no faults or MIL associated with this symptom.
Customer Observations or Concerns:
Intermittent shutdown
Coming to a stop
At idle

SPECIAL TOOL(s) / SOFTWARE
Tool Description

Tool Number

Comments

Instructions

SDS

N/A

N/A

N/A

Tools Resource Center

SERVICE PARTS INFORMATION
Please consult your parts department for service part information. Ensure you are using the most current part numbers.

IMP Isolation Kit Parts
Outside Part
Source

Part Description
5/16" Fuel Line Clamp 304 Stainless Steel,
Adjustable 1/2 - 9/16 dia.

Amazon

Comments
Can be sourced from a local auto parts store. Recommend 304 stainless steel
to prevent rust/corrosion.

Fuel Line 5/16 inch ID NBR Fuel Line Hose, Rubber. Amazon

Can be sourced from a local auto parts store.

Adapter, M10X1.0 >> 5/16" Barb

Can be sourced from a local auto parts store. Recommend anodized aluminum
to prevent corrosion.

Racetronix

DIAGNOSTIC STEP(s)

Step

Health report review.
Review the initial health report as well as telematics reports (if available) for
any relevant DTCs related to engine performance:
Were any faults related to engine performance found, such as fuel-system, intake
manifold pressure faults, misfire faults, or engine speed at idle faults?

Decision
Yes.
Perform the published diagnostics for the
associated fault code.

#1
No.
Proceed to step 2.

Step
#2

Verify ECM calibration

Decision

Confirm the ECM calibration is up to date:

Yes.

Is the ECM calibration software ****TK*A or greater?

Proceed to step 3.

No.
Update the ECM calibration and then
proceed to step 3.

Step

IMP sensor inspection.
Inspect the intake manifold pressure (IMP) sensor body for the Julian date
code. See Image #1 for example:

Decision
Yes.
Proceed to step 4.

Is the IMP date code 3152 or greater?

No.
#3

Step

Replace the IMP sensor with a date code
greater than 3152. Then proceed to step
4.

Inspect the flywheel timing mark.

Decision

Reference and follow the iKNow article IK1201498:

Yes, the IMP sensor was replaced, and
the article required a shim to be
Was the IMP sensor replaced in the previous step? Did the IKNOW article require a installed.
shim to be installed on the crankshaft position sensor?
Re-test for the symptom. If the issue
NOTE: Once the IKNOW article has been referenced, this article should
persists, proceed to step 5.
continue to be followed. If the article leads to a flywheel replacement, DO NOT
replace the flywheel.
No, the IMP sensor was not replaced,
but the article required a shim to be
installed.
Re-test for the symptom. If the issue
persists, proceed to step 5.
#4
No, the IMP sensor was replaced, but
the article did not require a shim to be
installed.
Re-test for the symptom. If the issue
persists, proceed to step 5.
No, the IMP sensor was not replaced,
nor did the CKP sensor require a shim
to be installed.
Proceed to step 5.

Step
#5

Confirm base airflow.

Decision

Perform an Air Management Test (AMT).

Yes.

Select the halfway point between the VGT Actuator command to 60% and
EGRV command to 100%, see Image #2 for selection point example:

Proceed to step 6.

Is MAF between 1200 - 1500, IMP between 10 - 20, and EBP between 20 - 40?

No.

NOTE: To access a GUIDE session with no active fault, follow the steps below;

1. In Service Portals "Master Service Information", select "Service Information by
VIN" at the bottom right of the selection table.
2. Enter the last 8 of the VIN in the "Chassis" field.
3. Search By "Fault Code Action Plan".
4. Enter the source address as "0", Fault type as "SPN132", and FMI as "16",
then hit "search".

Step

Perform a GUIDE session for SPN 132
FMI 16. If the symptom persists, proceed
to step 7.
NOTE: If the GUIDE session leads to a
NOX sensor replacement, do NOT
replace the NOX sensor, as it's likely
not the cause of the shutdown
complaint.

Check for biased sensors.
Perform a 5-minute KOEO signal monitor session with SDS.

Decision
Yes.

Review the session and confirm the IMP sensor is reading 0, EBP centerline is Proceed to step 8.
equal to or less than 0.25 psi, and MAF sensor is reading less than 25 kg/hr
without fluctuating. See Image #3 for KOEO example:
Are all sensors reading as intended?

#6

No.
Proceed to step 7.

Step

Check for biased sensors

Decision

Disconnect and reconnect the identified biased sensor.

Yes.

Perform another 5-minute KOEO signal monitor session with SDS:

Replace the identified sensor, and then
re-test for the symptom. If the symptom
persists, proceed to step 8.

Is the previously biased sensor still reading biased?

NOTE: If replacing the EBP sensor,
confirm the tube is free from restriction
and/or damage.
#7
No.
Replace the connector body and pins on
the identified sensor, and then re-test for
the symptom. If the symptom persists,
proceed to step 8.

Step
#8

Check for biased sensors.

Decision

Perform a 5-minute KOER signal monitor session with SDS.

Yes.

Review the session and confirm IMP is at or close to 0, and EBP is fairly
steady and below 10 psi. See Image #4 for KOER example:

Proceed to step 10.

Are the sensors reading as intended, and not fluctuating rapidly?

No.

Proceed to step 9.

Step

Check for biased sensors

Decision

Disconnect and reconnect the identified biased sensor.

Yes.

Perform another 5-minute KOER signal monitor session with SDS:

Replace the identified sensor, and then
re-test for the symptom. If the symptom
persists, proceed to step 10.

Is the previously biased sensor still reading biased?

NOTE: If replacing the EBP sensor,
confirm the tube is free from restriction
and/or damage.
#9
No.
Replace the connector body and pins on
the identified sensor, and then re-test for
the symptom. If the symptom persists,
proceed to step 10.

Step

Confirm engine performance.

Decision

Perform a 0-60 / Lugdown

Yes.

Review DPF Differential Pressure, Intake Manifold Pressure compared to
desired, and Fuel Rail Pressure compared to desired:

With customer permission, install an IMP
isolation kit. Review the parts information
and kit installation instructions.

Is DPF Differential Pressure below 0.5 psi, the Intake Manifold Pressure meeting or
exceeding desired values, and the Fuel Rail Pressure following desired values?

No, DPFDP is above 0.5 psi.

NOTE: IMP and FRP may not exactly follow desired values as the transmission Remove the DOC and DPF for inspection.
shifts gears, and the engine RPM drops drastically. The values should be
Inspect them per the re-use guidelines in
reviewed while the engine RPM is climbing and the engine is under load.
the manual. If they pass for re-use, have
the DOC cleaned, and the DPF cleaned
DPFDP example - Image #5
and baked.
IMP example - Image #6
#10 FRP example - Image #7

Once completed, re-test for the symptom,
and if the symptom persists, follow the
"yes" result from this step.
No, IMP is not meeting or exceeding
desired values.
Locate the source of low airflow.
IK1201511 can be followed to assist with
diagnostics.
No, FRP is not following desired
values.
Locate the source of FRP issues.
IK1500110 can be followed to assist with
diagnostics.

Step #2 - Image #1: IMP Date Code

Step #4 - Image #2: AMT review selection point
Item 1: AMT Selection Point

Step #5 - Image #3: KOEO
Item 1: Normal EBP reading
Item 2: Normal IMP and MAF values at KOEO

Step #7 - Image #4: KOER

Item 1: Normal EBP fluctuation.
Item 2: IMP should typically read 0 psi at idle.

Step #9 - Image #5: DPF Differential Pressure

Step #9 - Image #6: Intake Manifold Pressure vs. Desired
Item 1: Example of IMP dropping below desired. Should be considered normal when engine RPM drops due to shift events.

Step #9 - Image #7: Fuel Rail Pressure vs. Desired
Item 1: Example of FRP lagging slightly behind desired during shifting events.
Item 2: Recommended selection point. Final gear shift, engine under load.

REPAIR STEP(s)
Please see the service manual for current service and repair procedures.

IMP Isolation Kit Installation Instructions
/service_kb/DocTool/Documents/Published/IK1201516/Files/IMP Sensor Isolation Test.pdf
Return to step 10.

WARRANTY INFORMATION
Warranty Claim Coding:
Refer to the Warranty Coding Manual for Group and Noun Codes.

Standard Repair Time(s):
Refer to the SRT Manual for Repair Times

OTHER RESOURCES
Master Service Information Site

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