DEF sender

[Boatworker]

A couple of days ago, we were moving the coach from the desert up to it's summer home in Paso Robles. We do this in two legs with a stop in between. About 30 minutes into the first day the DEF, MIL and Check Engine lights came on. Also, the DEF gauge went from 1/3 to Full.



Other than an alarm every few minutes, everything else seemed normal. All temps and pressures were in there regular spots.Having read about sender issues in the past, I figured that was the problem, and seeing that it was Sunday I just carried on. About a hundred miles later everything returned to normal and we reached our first stop without any more issues.


Called Tiffin on Monday and they confirmed that it probably was the sender. The tech said not to add any DEF, once the engine was started not to shut it off and if the Red check engine light came on that it would go into Limp Home mode at 5 MPH. He also said they would ship another sender unit.



Engine started and ran fine, and other than the MIL light everything was normal during the next couple of hundred miles to our destination.


I received the new sender yesterday just a day after my conversation with the tech! So, my question is, what am I looking at as far as replacing it. The tech said it takes about 2 1/2 hours but I'm guessing that is for someone that has done it a few times. It's obvious the tank has to come out. What's not obvious is how to accomplish that. Any words of wisdom would be appreciated.


Thanks,

[garykk]

The panel covering the radiator which on ours also includes the def door has to come off. It’s a few screws and bolts, about 5 or 6. Once that’s off, the tank should be exposed. There is a bracket on the bottom of the steel shelf the tank sits on, this has to come off with one bolt. But if it’s lo,e ours, I had to cut off the small tab on the left end as there was not enough room to get it off other wise . I then just welded a small straight tab on to the bracket later.
Next, remove the radiator cap to release any pressure. On the tank there are two electrical connections that have to be disconnected. The two coolant hoses with small screw clamps and two lines for def fluid, one has a black tab, the other green. Remember their position or take a photo before. Push in on the colored tabs and pull the connection off.
The tank can be removed then.
The sensor unit is pressed in, sealed with large o ring. Remove the locking ring with what I recall is two small screws. The sensor unit can then be gently pried up till you can pull it out.
I emptied the def tank before I did this as the fluid was old and I wanted to clean the tank anyway and have fresh fluid.
Reverse procedure.
It took me about 3 hrs but now could do it in half the time.
Have fun.
The MILs will remain until about 3-4 cycles.

[Boatworker]

Thanks Gary, but ours is a rear radiator unit. The DEF tank is in the same compartment as the shore power reel. Although once I figure out how to get it out, I'm pretty sure the rest of the procedure will be the same.

[BoeingSWTech]

Here are some instructions on how to remove and replace the DEF Sensor head. This instruction is shown on just the plain powerglide chassis with no RV body installed. So you will have raise the back end of your 40IH as high as possible (don't lift the wheels off the ground) and drop the DEF tank under the RV to get access to the DEF Sensor head. I hope this helps. There has been a lot of folks with this issue. Another good source of information since you are a 40IH owner is FB group Tiffin Phaeton 40IH & 44OH Owners. This forum and the other group really provide excellent information to help keep you on top of of your RV maintenance. Good luck.

[garykk]

Originally Posted by BoeingSWTech

Here are some instructions on how to remove and replace the DEF Sensor head. This instruction is shown on just the plain powerglide chassis with no RV body installed. So you will have raise the back end of your 40IH as high as possible (don't lift the wheels off the ground) and drop the DEF tank under the RV to get access to the DEF Sensor head. I hope this helps. There has been a lot of folks with this issue. Another good source of information since you are a 40IH owner is FB group Tiffin Phaeton 40IH & 44OH Owners. This forum and the other group really provide excellent information to help keep you on top of of your RV maintenance. Good luck.

You can’t drop the tank, it has to be slid out of the compartment.

[BoeingSWTech]

Garykk - On the 2018 40IH you have to drop the DEF tank out of the bottom of the RV by removing the 4 bolts (blue arrows, 2 inboard and 2 outboard) in lower support tray. These bolts can be accessed under the RV. The DEF tank instructions that I attached provide general guidance for the connections to the DEF sensor. Boatworker has a 2018 40IH just like mine. I have attached a picture below so you can see how they are different from your bus. Hope this helps.

[NLOVNIT]

May I ask, is changing out that head part of maintenance, like changing the AquaHot nozzle is? Also, is this considered part of a chassis service? I'm just wondering because I, too, have a 2018 40IH & don't want to run into a limp mode circumstance. We're the 2nd owners of our coach & I have no records of what the PO did as far as maintenance. I've gotten everything but chassis service taken care of & that is scheduled for next Tues with a Tiffin authorized PG service center.

TIA!

Lori-

[BoeingSWTech]

Changing out the DEF sensor unit is not part of your normal maintenance schedule. Some of the Powerglide chassis had faulty GEN 5 sensors installed. Tiffin is aware of the situation and has been overnighting a replacement GEN 6 sensor to those who have run into this issue with their unit. Should this happen in your future, you can contact Ricky at Tiffin and he will help you through the process.

[iowaone]

It would be a very expensive maintenance item!

[dwaugh10]

Is there any way to tell a Gen 5 from a Gen 6 sensor?

[garykk]

Originally Posted by BoeingSWTech

Garykk - On the 2018 40IH you have to drop the DEF tank out of the bottom of the RV by removing the 4 bolts (blue arrows, 2 inboard and 2 outboard) in lower support tray. These bolts can be accessed under the RV. The DEF tank instructions that I attached provide general guidance for the connections to the DEF sensor. Boatworker has a 2018 40IH just like mine. I have attached a picture below so you can see how they are different from your bus. Hope this helps.

Thanks, wish mine would have been that easy

[garykk]

Originally Posted by BoeingSWTech

Changing out the DEF sensor unit is not part of your normal maintenance schedule. Some of the Powerglide chassis had faulty GEN 5 sensors installed. Tiffin is aware of the situation and has been overnighting a replacement GEN 6 sensor to those who have run into this issue with their unit. Should this happen in your future, you can contact Ricky at Tiffin and he will help you through the process.

And Tiffin will not change them out until they fail Ours went out at just under 20k miles. Fortunately for us, it was parked in our yard. Tiffin overnights the new sensor.

[Boatworker]

Originally Posted by BoeingSWTech

Here are some instructions on how to remove and replace the DEF Sensor head. This instruction is shown on just the plain powerglide chassis with no RV body installed. So you will have raise the back end of your 40IH as high as possible (don't lift the wheels off the ground) and drop the DEF tank under the RV to get access to the DEF Sensor head. I hope this helps. There has been a lot of folks with this issue. Another good source of information since you are a 40IH owner is FB group Tiffin Phaeton 40IH & 44OH Owners. This forum and the other group really provide excellent information to help keep you on top of of your RV maintenance. Good luck.

Thanks. This really helps.

[NLOVNIT]

Originally Posted by dwaugh10

Is there any way to tell a Gen 5 from a Gen 6 sensor?

X2 on that question. If I call Tiffin with my VIN, they should know, right? Our coach came off the assembly line in Dec 2017 - which seems to me to be about half way thru the model year production.

Originally Posted by garykk

And Tiffin will not change them out until they fail Ours went out at just under 20k miles. Fortunately for us, it was parked in our yard. Tiffin overnights the new sensor.

Great.....NOT!

Lori-