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Old 07-26-2021, 08:12 PM   #1
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Brand: Thor Motor Coach
Model: Siesta 24SS
State: California
Posts: 1,710
THOR #12698
Sprinter and the Limp Mode

On this last trip which started in California and went to Kentucky and many points between before we made it back to California, my 2018 Thor Siesta 24SS which is built on a 2017 Mercedes Benz 3500 Chassis gave me some issues along our way. On a steep grade towing our car, the outside temp in Arizona hit 117. We were not over heating, but during that climb the engine went into limp mode slowing us down to about 20 mph. Once I got to the top and started down hill, everything went back to normal. Fast forward a couple of weeks and a couple of 1,000 miles, while in Arkansas once again climbing a grade and it was above 100 outside we went back into limp mode. I discovered that if I pulled over and shut the engine off and restarted, it would clear up and go back to normal. This happened another 8 more times on our return trip. During three of those moments, I got a check engine light on the dash. Each time the dash light would reset either after we stopped for the night or while driving. Once I got home, I pulled out my OBD11 scanner and got code P2428. That code states that the exhaust gas temperature is high. It was recommended that the exhaust temp sensor before the turbo as well as the one after be tested and replaced as necessary. I made an appointment with my local MB dealership and took it to them the following week. They scanned the system and told me they needed to keep it overnight to test it when the engine is cold so I left it. 2 days later they called and said that they could not locate the issue except that their check should two codes(temp sensor and boost code). They were going to conduct a test drive to watch the system as they drove it on some hill climbs and it once again went into limp mode. They decided to keep it and talk to one of the Mercedes Engineers to try and determine the cause of these issues. This has been the only issue I have had with this chassis and hopefully the engineer can direct them to the problem soon. We have another trip scheduled for 08/07/21. Our back up plan is to take the car if the motor home is still out of commission.

Paul

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Old 07-26-2021, 11:23 PM   #2
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Brand: Thor Motor Coach
Model: 24TF Compass / Mercedes
State: New York
Posts: 123
THOR #17969
Keep us in the loop as to the outcome. Hopefully you're back to trouble free motoring shortly.
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Old 07-27-2021, 12:04 AM   #3
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Brand: Thor Motor Coach
Model: Siesta 24SS
State: California
Posts: 1,710
THOR #12698
I just received a letter from Mercedes with an extension on the Exhaust Gas Turbocharger for model years 2010-2019. They are extending the warranty to 11 years or 120,000 miles on that component only. Not sure yet if that is part of the problem with my unit. They are still checking into the problem.

Paul
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Old 07-27-2021, 12:36 AM   #4
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Brand: Still Looking
Model: Tiffin Wayfarer 24 BW
State: New York
Posts: 21,732
THOR #8860
Hi Paul,
Glad to hear that they made things right for you!
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Old 07-29-2021, 11:39 PM   #5
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Brand: Thor Motor Coach
Model: Siesta 24SS
State: California
Posts: 1,710
THOR #12698
I had a tune installed on my Sprinter to increase horsepower and torque only back in Feb. 2021. I now think the tune is causing a conflict within the Sprinter computer system. I decided to pick up the motor home tomorrow and take the ECU out to have the shop that installed the tune remove it and install the factory settings. The MB tech felt the tune was causing a conflict within the system. Hopefully the system will revert back with no further issues(fault codes and limp mode). The shop that installed the tune said they can remove it and place the factory settings back into place.

Paul
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Old 08-15-2021, 02:37 AM   #6
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Brand: Thor Motor Coach
Model: Siesta 24SS
State: California
Posts: 1,710
THOR #12698
After leaving my Sprinter motor home at my local Mercedes Benz dealership, they replaced a total of 4 sensors and had the tech test drive it 4 times(test drive one time after each sensor was replaced). During each test drive, the Sprinter went back into limp mode. I then explained to them that I had a tune installed in the ECU and was wondering if that could be the reason for the limp mode and codes it was displaying. They thought the tune might be the reason and suggested removing it. Based on that recommendation, I took the ECU back to the shop that installed the tune and had it removed. The factory settings were restored. I then took it on a 1400 mile round trip to Utah from California climbing many steep grades in high heat while towing our 2014 Ford Flex. I experienced ZERO limp modes and no fault codes. It appears the tune that was installed was conflicting with the engine computer unit causing the issues we experienced during our 5,000 mile cross country trip this summer. At this point I have no further plans on installing another tune and will leave the Sprinter computer alone.

Paul
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Old 08-15-2021, 03:38 AM   #7
I Think We're Lost!
 
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Brand: Still Looking
Model: Tiffin Wayfarer 24 BW
State: New York
Posts: 21,732
THOR #8860
At least the source of the problem was found and fixed.
Sorry to hear that it was the "tuned-up" chip...
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Old 08-15-2021, 12:07 PM   #8
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Brand: Thor Motor Coach
Model: Axis 24.1
State: Connecticut
Posts: 889
THOR #20289
I am amazed that your Mercedes dealer couldn't immediately detect an altered tune status. If they had I suspect they would have then returned the vehicle to you and said it is your problem to fix.

Sounds like they wasted a dozen hours of service work on this tune related problem. If I were them I would be pissed and might ask you to pay for their work.

I would never, ever alter a factory state of tune.

David
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