DEF Main Sensor

[389 Hood]

The main sensor that regulates the temperature, injection rate and a host of other things went bad on me Tuesday morning. The DEF gauge dropped to 0, the low fluid indicator came on, the check engine light came on and it threw a couple of codes. Then it gave me 4 hours of drive time until it went it ' 40% derate' mode. After the 4 hour derate timer expires, it goes into limp mode which is 5 MPH.

I was able to get it back to the yard with no operability issues. It would intermittently operate, but the codes were still set. I called the closest dealers to me. They are telling me it could be up to 12 weeks for a replacement unit. They are allowed only one unit per day, per dealer and they have a backlog sitting in the shop waiting. I called up a buddy who recommended his mobile fleet service. He came out, hooked up his laptop and told me what it would be before he even looked. He was right.

He has a direct connection with the manufacturer and said he could get it by the end of the week. I told him to overnight it if he could get his hands on one. This same sensor is used in just about all heavy equipment with a few differences, but for off road equipment it was available.

I inquired about 'turning off', the DEF system, just to be able to use the truck until the part came in, but in order to do that, you have to delete the program from the ECM, remove the DPF and bore holes into another part to alleviate the back pressure in the exhaust. Then when the repair is made, you have to reinstall the operating program back into the ECM and replace the DPF. That software is $2500.

Looks like that 'Honey-Do' list is going to shrink this week.

 

[Mike]

The thought of a breakdown right now is scary. A simple part can put someone out of business these days.

 

[389 Hood]

It's even scarier if you're 1000 miles from home and know no one to help you.

 

[mndriver]

Think how I feel knowing I need a 6-pack right now.

 

[Rigjockey]

When we get in a situation where it says engine in derate we pull the speed sensor. The only things are you have no speedometer, odometer and the truck wont go above 1400 Rpm.
Is that something that could work in your case?

We do that when the truck wont re-gen, so it may be a bit different.

 

[389 Hood]

It never reached derate. But wouldn't unplugging the speed sensor show as no mileage accumulated on the ELD? Or is that set to operate off of GPS?

I could easily get by by running 1400 rpm's. That would leave me with a top end of about 70. That would be a chance I'm not wanting to take out there at night. Daytime, may be different. And if something did go wrong, I have to explain to my boss about the $2500 towing bill.

 

[Electric Chicken]

It never reached derate. But wouldn't unplugging the speed sensor show as no mileage accumulated on the ELD? Or is that set to operate off of GPS?

I could easily get by by running 1400 rpm's. That would leave me with a top end of about 70. That would be a chance I'm not wanting to take out there at night. Daytime, may be different. And if something did go wrong, I have to explain to my boss about the $2500 towing bill.

ELD currently expects an odometer/device match. Every now and then ours requires us to input the odometer reading for calibration. I've had mileage where the shop unplugged the box from the OBD port to take it for test drives, and when I got it back it only asked me to calibrate the mileage.

But I wasn't on duty or driving under dispatch either.

 

[389 Hood]

Into the third week trying to get a sensor. No matter where I call, I get a flat "Not Available".

I'm grateful to work for a company that continues to pay me while not generating a dime of revenue.

I told my boss to delete the software, hog out the exhaust and drive the truck. When the new ones finally become available, sell the truck for export to the Islands or South America. I never got an answer on that one. Are there really states out there that do emissions testing on big trucks or even inspections on the systems? Just remove the DPF and associated internal equipment and leave all of the wiring in place so it looks proper.

 

[Electric Chicken]

I'd like to go back to the old Ford if I get my own authority. No one would be able to tell me I need X year truck. Your experience is why. That's why I haven't sold it yet, or even tried to. I'm hoping I can get ahead of the curve enough to start throwing full restomod money at it. Updated hubs, sound deadening, bodywork, paint, plush interior even if I have to fab some stuff, 13 DO, air ride cab, etc.

It's a dead ass simple truck and I think it would be a better "this is my last truck ever truck" than the Mack.

 

[RocketScott]

Seems like bad QLSs are a common problem now. There is an issue with the tank heater valve getting stuck open, overheating the DEF, and frying the sensor. Check the heater hose going to the tank and see if it's hot. You may need to replace the solenoid

Keep an eye on the RV forums. All it takes is pissing off the right retired techie with a diesel pusher. On one forum there are guys working on a device to spoof the sensor. Basically sending the ECM what it wants to hear so it won't derate. They are able to do that right now but are working on making it simpler so the average person can build one

It's not as simple as putting a resistor into the sensor wire. The sensor sends out sentences of data. I'm still trying to come up to speed on the truck systems. Have experience with boat systems that are very similar (NMEA 2000), just a slightly different vocabulary between sensors and brains

All this is probably going to backfire on the engine manufactures and the EPA since they aren't working hard enough to solve this issue. It won't be long till unlocking an engine will be as commonplace as unlocking a phone

 

[389 Hood]

I had a problem 2 years ago with the tank heater sensor. It took a week to get that sensor and have it installed. I need to do some research as to the temperature range of the DEF as it's injected. It may only need to be warmed below a certain temperature. It's a rarity that encounter ambient temps below 35F.

 

[Mike]

Into the third week trying to get a sensor. No matter where I call, I get a flat "Not Available".

I'm grateful to work for a company that continues to pay me while not generating a dime of revenue.

I told my boss to delete the software, hog out the exhaust and drive the truck. When the new ones finally become available, sell the truck for export to the Islands or South America. I never got an answer on that one. Are there really states out there that do emissions testing on big trucks or even inspections on the systems? Just remove the DPF and associated internal equipment and leave all of the wiring in place so it looks proper.

I have heard of people bypassing the coolant plumbing into this system as a temp fix right now, since it is clearly warm enoug right now that there is no heat needed.

 

[389 Hood]

But it's the quality sensor at this point, not the temperature sensor. At least that's what the diagnostics are showing. I never had any issues buying the cow piss at the T/A, but this is a purchase from the Crooked Hook, that's in there now and it took 350 miles to show it's ass.

I found an outfit in Davie FL. that makes the sensors and tanks, but they are not forthcoming with any stock info to me. They do not deal with the end user. Which to me is BS! What if I am the shop and the end user?

Why the problem can't be diagnosed and the issue corrected, then the sensor mapping be reset? Planned obsolescence.