performed again.

#12

If the issue persists, proceed to step 13.
NOTE: International no longer requires
or provides iApprovals for DOC or DPF
replacements.

Step

Validate airflow

#13 Review the 0-60/Lugdown snapshot from step 12
Graph IMP vs. IMP desired:
Is IMP meeting or exceeding desired values throughout?

Decision
Yes.
Replace the NOX-IN sensor, perform a
MAF calibration, and then re-test for the
issue.

NOTE: This should be reviewed during an acceleration or steady state portion If the issue persists, open a tech service
of the snapshot. The IMP may drop below desired values during decel, and
case file providing the step-by-step results
shouldn't be used for this step to determine a failure.
with numerical readings where applicable
from this article, and other published
diagnostics completed.

No.

Proceed to step 14.

Step

Locate the source of low-airflow.
Perform smoke testing on the intake and exhaust, and CAC pressure testing,
to determine if we have a leak:

Decision
Yes.
Perform repairs/replacements as needed
and then re-test.

Was a leak identified?

If the issue persists, perform a fresh 060/Lugdown, and perform step 13 again.

No.

#14

Replace the VGT (turbo) assembly,
perform a MAF calibration, and then retest for the issue.
If the issue persists, perform a fresh 060/Lugdown, and perform step 13 again.

2021 A26 ESN 4600000 - 4699999
Step

Confirm base diagnostics have been completed.
Review FCAP/GUIDE and symptom-based diagnostics from the diagnostic
manual:
Did the applicable FCAP/GUIDE or symptom-based diagnostics identify a repair
path?

Decision
Yes.
Follow the repair path established by the
published diagnostics.

NOTE: If there is a symptom associated with the fault code, the diagnostics for
that symptom should be performed before moving on to the next step.

#1
No.
Proceed to step 2.

Step
#2

Confirm ECM calibration

Decision

Confirm the ECM calibration is up to date:

Yes.

Is the ECM calibration TK*A or greater?

Proceed to step 3.

No.
Update the ECM calibration and then retest for the issue. If the issue persists,
proceed to step 3.

Step

Review health reports
If the ECM calibration was already up to date, review the health report history
from the past 100 engine hours. Check for VGT (641) fault codes.

Decision
Yes.
Proceed to step 4.

If the ECM calibration was updated, confirm a VGT (641) fault did not log
pending or active when re-testing:
Were any VGT faults found, without associated repairs?

#3

No.
Proceed to step 5.

Step

Inspect the VGT

Decision

Disconnect the VGT actuator linkage from the turbo. Cycle the turbo vanes by Yes.
hand both cold and hot, to check for binding/sticking:
Replace the turbo assembly, perform a
Was any binding or sticking found when sweeping the VGT (turbo) vanes?
MAF calibraiton, and then re-test for the
issue. If the issue persists, proceed to
NOTE: Do NOT turn the key-on while the actuator arm is disconnected from
step 5.
the turbo, as this can cause damage to the assembly.

#4

No.
Proceed to step 5.

Step

Confirm EGRV operation
Perform an Air Management Test and inspect for EGRV operation per Image
#1:
Was a failed EGRV identified?

Decision
Yes.
Replace the EGRV, perform a MAF
calibration, and re-test for the issue. If the
issue persists, proceed to step 6.

NOTE: At the selection point in Image 1, the EGRV should be 0.00% when
commanded is 0.00%. If it is not, this should be considered a failed EGRV.
NOTE: If the EGRV was replaced,
another AMT should be completed
before proceeding to step 6.
#5

No.
Proceed to step 6.

STEP 5

Item 1: Selection point of the AMT
Item 2: Example of EGRV position blowing open from commanded position

Step

Validate airflow.
At the same point in the graph the EGRV was checked (halfway between VGT
command and EGRV command positions start), verify the Mass Air Flow,
Intake Manifold Pressure, and Exhaust Back Pressure readings:

Decision
Yes.
Proceed to step 7.

Is MAF below 1100 kg/hr, IMP below 10 psi, and/or EBP below 20 psi?

#6

No.
Proceed to step 8.

Step
#7

Locate the source of low-airflow.
Perform smoke testing on the intake and exhaust, and CAC pressure testing,
to determine if a leak is present:
Was a leak identified?
NOTE: The link for the exhaust smoke testing is to the 2017 manual. The
process and tools should be the same, and the steps can be followed still.

Decision
Yes.
Perform repairs/replacements as needed
and then re-test. If the issue persists,
proceed to step 9.

No.
Proceed to step 9.

Step

Validate airflow.
At the same point in the graph the EGRV was checked (halfway between VGT
command and EGRV command positions start), verify the Mass Air Flow,
Intake Manifold Pressure, and Exhaust Back Pressure readings:
Is MAF above 1500 kg/hr or IMP above 25 psi, with EBP above 45 psi and/or
DPFDP above 0.4 psi?

#8

Decision
Yes.
Drop the DOC and DPF for inspection.
Inspect them per the re-use guidelines to
determine if they can be reused or if they
should be replaced. If they can be
replaced, have the DOC cleaned, and the
DPF cleaned AND baked. Once repairs
are completed, re-test for the issue. If the
issue persists, proceed to step 9.
NOTE: International no longer requires
or provides iApprovals for DOC or DPF
replacements.

No.
Proceed to step 9.

Step

Check for biased sensors.
Perform a 5-minute KOEO signal monitor session with SDS. Review the
session and confirm the EBP sensor, IMP sensor, and MAF sensors are
reading 0 with the engine off:

Decision
Yes.
Proceed to step 11.

Are all of the listed sensors reading 0 at KOEO?

#9

No.
Proceed to step 10.

Step

Confirm the circuits to the identified biased sensor.

#10 Perform connector body, pin drag, pin inspections, and circuit checks at the
biased sensor (connector and pins should be inspected at each connection
point):
Was a failed connector/pin identified, or was a failed circuit identified?

Decision
Yes.
Repair/replace the failed connector/pin or
replace the engine sensor harness and
re-test. If the issue persists, proceed to
step 11.

No.
Replace the biased sensor and re-test. If
the issue persists, proceed to step 11.

Step

Perform a regen.

Decision

Perform a regen and review per IK1201494:

Yes.

Was an issue found during the regeneration diagnostics?

Perform repairs as needed and then retest for the issue. If the issue persists,
proceed to step 12.

#11

No.
Proceed to step 12.

Step

Validate Airflow

Decision

Perform a 0-60/Lugdown and road test during a signal monitor session in SDS. Yes.
Review DPFDP:

Proceed to step 13.

Is DPFDP lower than 0.5 psi throughout the entire snapshot?

No, DPFDP is greater than 0.5 PSI.
If the DPF was already cleaned AND
baked (not just cleaned), replace the DPF
and re-test. If the issue persists, validate
the results of this step with a new/current
0-60/Lugdown.
If the DOC and DPF have not been
inspected per the reuse guidelines, do so
at this time. If they pass re-use, have the
DOC cleaned and the DPF cleaned AND
baked. If they were not cleaned AND
baked before this step, another 060/Lugdown and this step should be
performed again.

#12

If the issue persists, proceed to step 13.
NOTE: International no longer requires
or provides iApprovals for DOC or DPF
replacements.

Step

Validate airflow

#13 Review the 0-60/Lugdown snapshot from step 12
Graph IMP vs. IMP desired:
Is IMP meeting or exceeding desired values throughout?

Decision
Yes.
Replace the NOX-IN sensor, perform a
MAF calibration, and then re-test for the
issue.

NOTE: This should be reviewed during an acceleration or steady state portion If the issue persists, open a tech service
of the snapshot. The IMP may drop below desired values during decel, and
case file providing the step-by-step results
shouldn't be used for this step to determine a failure.
with numerical readings where applicable
from this article, and other published
diagnostics completed.

No.
Proceed to step 14.

Step

Locate the source of low-airflow.

Decision

Perform smoke testing on the intake and exhaust, and CAC pressure testing,
to determine if a leak is present:

Yes.
Perform repairs/replacements as needed
and then re-test.

Was a leak identified?
NOTE: The link for the exhaust smoke testing is to the 2017 manual. The
process and tools should be the same, and the steps can be followed still.

If the issue persists, review step 13 again.

No.

#14

Replace the VGT (turbo) assembly,
perform a MAF calibration, and then retest for the issue.
If the issue persists, review step 13 again.

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

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

Hide Details

Feedback Information
Viewed:

683

Helpful:

5

Not Helpful: 1
No Feedback Found

Copyright © 2025 Navistar, Inc.