Solution K08315540
Friday, July 26, 2019 7:43:22 PM CEST

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** SOLUTION **

Title Mack Chassis - LEU, MRU, LR - Frequent Requests For Regeneration, ( Hourly To
Daily ); Possible High Soot Load Warnings And Fault Codes Or Accelerated Soot
Accumulation - Previously Tech Tip TT-020-2015 - US10 And Newer (Includes GHG17
(US17, Common Rail) Emissions, Common Model Years 2011 And Newer

“Mack Models

Mack Model L LR, MRU - TerraPro

mission Standar

Emission Standard US10, US10+OBD13, US14, USI4+OBD15, US14+OBD16, US14 CNG, US17
US17+OBD16, USI7+OBD18

ngine family

Engine family MP7, MP8
SOLUTION
Cause Cabover vehicles equipped with a Selective Catalytic Reduction (SCR) muffler may

experience frequent requests for parked regens, high soot load warnings, fault codes for

soot level, or a combination of all three.

Other common symptoms include:

- High inlet (T1) exhaust temperatures during high engine load, most commonly during
highway operation.

+ Temperatures of 840 °F (450 °C) or greater would be considered excessive.

- Following Fault codes are possible, P111C-00, P1151-00, P2201-64, Soot related
codes (P10FE-00, P24A4-00, P2463-00, P244B-00, P10E1-00 and P2459-00).

- Low NOx levels at the Inlet NOx Sensor (Sensor 1) during high engine load, most
commonly during highway operation.
+ NOTE: Itis not possible to observe the inlet NOx value for US10 chassis
(Common model years 2011 to 2013, models with a 9-pin diagnostic connector). The
parameter does not return any sensor values when monitored during a road test.

Other symptoms will need to be used to confirm an issue for these chassis.

- High Diesel Particulate Filter (DPF) differential pressure (dP, delta-P) within 30 min

of performing

ul regen or reinstalling a cleaned/new filter,

Ss 1. Check the orientation of the exhaust stack screen.

1 - One of the common causes of frequent regen requests is exhaust mixing with fresh intake air.

u - The exhaust stack screen should be pointed outward, away from the vehicle. A screen that is turned to the front, the

inward can cause a buildup of exhaust gases near the intake that can be pulled in with fresh air. The photos below prc

examples of properly and improperly oriented exhaust screens:

7S!

Correct Tnconeet

2. Check the intake scoop

- Make sure the scoop is not secured too low on the intake pipe, creating an airflow restriction
3. Check the exhaust piping

- Aside from the screen orientation, ensure that there are no leaks in the exhaust piping and connections
4. Look for any wiring issues (fretting, paint etc) in the Diesel Particulate Filter (DPF) harness

- Wiring and connections should be checked all of the way from the sensors to the ACM for any damage , corrosi

or paint, ete.
5. Perform a snap throttle test
~ If the test results in a puff of smoke that clears quickly, the injectors can be eliminated as a possible cause.
6. Monitor exhaust backpressure
1. Install a transducer into the test port located at the DOC inlet
2. Observe the transducer readings with a multimeter set to millivolts. The reading translates directly into pounds
square inch gauge (psig, this is the notation for a difference in pressure).

3. Monitor the reading during a short road test that includes approximately 15 seconds of 100% throttle.

- If the maximum system back pressure never exceeds 3 psig (after a regen or clean DPF) the DOC and $CR can

eliminated as possible causes of high soot load.

7. Monitor DPF differential pressure

- During the road test in Step 6, if the DPF differential pressure never exceeds 1.2 psig, the DPF itself can be con
to be good.

8. Recommendations

- Always perform a basic physical inspection of the intake and exhaust systems when frequent regencrations are