DEF Head Failure. DPF Regeneration and start up procedure

[ThunderRidge]

Many threads now on DEF. I’m just trying to see if there are any common issues that go along with this? It doesn’t seem that the manufacturers of this equipment are in any hurry to solve this problem. We can keep throwing DEF heads at the problem or maybe with all the expertise and collective wisdom on these forums we can figure this out.

For those that have had the failure I noticed at times that a DPF Regeneration is sometimes recommended and tried as a fix. Also, the engine start procedure has been brought up as a possible problem.

If you had the DEF Head failure.

1. When you start your engine did you always wait for the yellow engine light to go out before starting? I believe this was so the computers read everything before the engine start.

2. Do you notice how often the DPF Regen message illuminates while you are driving? I suppose that somewhere there is some kind of parameter that causes the DPF Regeneration. The first time I ever got the message I didn’t know what it was for so I called Cummins. I was told the more you low idle and the more you are in stop and go situations, the more it will regenerate. I believe in my 1500 mile trip to Florida I noticed the DPF REGEN come on twice. Of course the majority of that was highway driving.

3. When you got the DPF REGEN message were you at highway speed and did you let the regeneration complete before shutting down the engine? Not at the coach now but, I thought the recommendation was to drive at highway speed until the light went out.

4. Do you idle your engine at low RPM for longer than it takes to air up? Again, not with the manual but, again I believe Cummins recommendation is no more than 2-3 minutes at low RPM idle.

5. Have you had to do a regeneration while parked? Since, the regeneration creates excessive amounts of heat and, that has also been mentioned as a culprit, I would think highway speed regeneration would be the best way. At least then there is some airflow to aid in cooling.

[Dutch Star Don]

Paul.....those are some pretty good questions. I argue that Cummins specifically, and Spartan and Freightliner to a certain degree, should come out and address all the myths and the EXACT cause for the DEF head failures. To me, it's unbelievable that they've remained silent and have not provided some comprehensive answers to the issue.

[ThunderRidge]

Don,
Hopefully, this will generate some thoughts on those that have had failures. Perhaps, they will be able to go back and determine if any of these factors or others stand out. Maybe there is a common denominator that we are just not seeing yet.

[flyboy013]

Originally Posted by ThunderRidge

1. When you start your engine did you always wait for the yellow engine light to go out before starting? I believe this was so the computers read everything before the engine start.

I never really paid attention to the check engine light when the key was turned on but before the engine started. There a various lights that are lite up without the engine running and I just figured this was one of them. My check engine light is slow to turn off. I think its a recent development. I have a stored in-active fault code relating to the DEF head being disconnected for an hour or so. Its a tamper related message. The date/time on the code corresponds to when North Trail replaced the DEF head. My guess is that they cleared the codes before everything was put back together. I'd like to have the code cleared, but not really sure I want to take it back to North Trail just to have them clear it.

2. Do you notice how often the DPF Regen message illuminates while you are driving?

I've noticed when the Regen takes place because I get the dash messages, but I haven't kept track. I don't think I've ever seen it start when I'm on the interstate.

3. When you got the DPF REGEN message were you at highway speed and did you let the regeneration complete before shutting down the engine?

I usually get the Regen message when I'm on roads with a speed limit of 55, but also has traffic lights. The Regen process stop when you slow down (35'ish) and then starts back up again when you speed up.

4. Do you idle your engine at low RPM for longer than it takes to air up?.

No, not usually.

5. Have you had to do a regeneration while parked?

I don't think this is possible since the Regen shuts off at low speeds.

[Dutch Star Don]

"flyboy013"....The yellow check engine light should be the last light to go out and should take 15-20 seconds. On both my 2014 DS and my 2019 DS, if I started the engine before it went out, it would throw a code about 30 minutes later. The light goes out after all the computers are done talking to each other.

I forget, but the code is something like SPN085 or SPN081, each occurrence, the code number increases by 1. So, the 4th time it did it, it was SPN081 -04. These codes will clear, but they take 5 start/stops with the engine running for at least 5 minutes each time. You may fine yours will go out after you reach the 5 starts and the there are no more thrown codes.

[flyboy013]

Originally Posted by Dutch Star Don

These codes will clear, but they take 5 start/stops with the engine running for at least 5 minutes each time. You may fine yours will go out after you reach the 5 starts and the there are no more thrown codes.

Thanks for the insight. I tried do the 5 ignition on/off cycles yesterday with no luck. Although I had read that they were supposed to be short cycles of a few seconds each without starting the engine). I then pulled out my BlueFire adapter in order to give it another try. It has a clear codes capability. After trying to clear the codes a few times I did get my 9 ABS related codes to clear. The problem was fixed some time ago but the codes were still stored as non-active codes. The DEF tamper fault did not clear.

[flyboy013]

Personally I don’t think the DEF Head failure is related to regeneration and I also don’t think its a Cummins issue. I’ve been doing a little bit of reading on DEF heads and here are my thoughts.


The DEF Head is a unit that contains three sensors: quantity, temperature, and quality. These sensors are connected to the CAN bus and report their value every so often (I haven’t yet determined the interval, but I suspect its probably around every 1-5 seconds).

It don’t think the sensors in the DEF Head are bad, keep reading.

Each fault code includes a Suspect Parameter Number (SPN). My were:

3364 (Aftertreatment 1 Diesel Exhaust Fluid Tank Quality)
1761 (Aftertreatment 1 Diesel Exhaust Fluid Tank Level)
3031 (Aftertreatment 1 Diesel Exhaust Fluid Tank Temperature)

For each fault there is a corresponding Failure Mode Identifier (FMI) which was 9 for each of these. A 9 indicates: Abnormal Update Rate. Basically, the sensors are not reporting at the consistent rate that the ECU is expecting. There are other codes for a sensor reporting data that too high, low, etc. My problem was that the update rate was abnormal.

So it would seem like the component in the DEF Head that puts the messages on the CAN bus is probably what’s bad as opposed to all three sensors going bad at the same time (unless there was some voltage surge that fried everything but then the sensors probably wouldn’t be reporting anything). Or its a microprocessor that (ie MCP2515) that reads the sensor data and generates the CAN Bus message.

So my guess is that we’re talking about a MCP2551 (High-speed CAN Transceiver) chip. A chip which costs about $1. Much less for a generic version. Or the MCP2515.

My 2 cents worth. Interested in thoughts others may have.

[96 Wideglide]

Originally Posted by ThunderRidge

3. When you got the DPF REGEN message were you at highway speed and did you let the regeneration complete before shutting down the engine? Not at the coach now but, I thought the recommendation was to drive at highway speed until the light went out.

Certainly try to, but it's not always possible.

I once had a regen start when I was about 3mi from the top of the mountain. Obviously when I went over the crest, I had to get off the throttle, and turn on the exhaust brake for the 12 or so mi descent.
Regen system didn't like that !

[Dutch Star Don]

Originally Posted by flyboy013

Personally I don’t think the DEF Head failure is related to regeneration and I also don’t think its a Cummins issue. I’ve been doing a little bit of reading on DEF heads and here are my thoughts.


The DEF Head is a unit that contains three sensors: quantity, temperature, and quality. These sensors are connected to the CAN bus and report their value every so often (I haven’t yet determined the interval, but I suspect its probably around every 1-5 seconds).

It don’t think the sensors in the DEF Head are bad, keep reading.

Each fault code includes a Suspect Parameter Number (SPN). My were:

3364 (Aftertreatment 1 Diesel Exhaust Fluid Tank Quality)
1761 (Aftertreatment 1 Diesel Exhaust Fluid Tank Level)
3031 (Aftertreatment 1 Diesel Exhaust Fluid Tank Temperature)

For each fault there is a corresponding Failure Mode Identifier (FMI) which was 9 for each of these. A 9 indicates: Abnormal Update Rate. Basically, the sensors are not reporting at the consistent rate that the ECU is expecting. There are other codes for a sensor reporting data that too high, low, etc. My problem was that the update rate was abnormal.

So it would seem like the component in the DEF Head that puts the messages on the CAN bus is probably what’s bad as opposed to all three sensors going bad at the same time (unless there was some voltage surge that fried everything but then the sensors probably wouldn’t be reporting anything). Or its a microprocessor that (ie MCP2515) that reads the sensor data and generates the CAN Bus message.

So my guess is that we’re talking about a MCP2551 (High-speed CAN Transceiver) chip. A chip which costs about $1. Much less for a generic version. Or the MCP2515.

My 2 cents worth. Interested in thoughts others may have.

Well, they keep talking about a chip shortage to fix this issue. It just amazes me that someone in this country can't duplicate the chip.

[Mikenat]

Originally Posted by ThunderRidge

Many threads now on DEF. I’m just trying to see if there are any common issues that go along with this? It doesn’t seem that the manufacturers of this equipment are in any hurry to solve this problem. We can keep throwing DEF heads at the problem or maybe with all the expertise and collective wisdom on these forums we can figure this out.

For those that have had the failure I noticed at times that a DPF Regeneration is sometimes recommended and tried as a fix. Also, the engine start procedure has been brought up as a possible problem.

If you had the DEF Head failure.

1. When you start your engine did you always wait for the yellow engine light to go out before starting? I believe this was so the computers read everything before the engine start.

2. Do you notice how often the DPF Regen message illuminates while you are driving? I suppose that somewhere there is some kind of parameter that causes the DPF Regeneration. The first time I ever got the message I didn’t know what it was for so I called Cummins. I was told the more you low idle and the more you are in stop and go situations, the more it will regenerate. I believe in my 1500 mile trip to Florida I noticed the DPF REGEN come on twice. Of course the majority of that was highway driving.

3. When you got the DPF REGEN message were you at highway speed and did you let the regeneration complete before shutting down the engine? Not at the coach now but, I thought the recommendation was to drive at highway speed until the light went out.

4. Do you idle your engine at low RPM for longer than it takes to air up? Again, not with the manual but, again I believe Cummins recommendation is no more than 2-3 minutes at low RPM idle.

5. Have you had to do a regeneration while parked? Since, the regeneration creates excessive amounts of heat and, that has also been mentioned as a culprit, I would think highway speed regeneration would be the best way. At least then there is some airflow to aid in cooling.

I have experienced two def head failures in two different Spartan chassis coaches to share and address your questions
1: my yellow engine light will not go off until the engine has been started. Goes off in less than 5 seconds
2:the regen indicator showing a regeneration in progress only seems to occur at highway speeds. Goes out after 20-30
minutes and do t know frequency.
3: regen only at highway speeds
4: idle while fueling and don’t believe the failures is caused by it
5: did a regen once at idle with a chip tool that forced the ecm to initiate the regen and clean the dpf. Lasted 20 minutes then went from high idle to idle.

My overall thoughts are that the failure is as posted… bad chip signals and that there is nothing wrong with the part itself. The ECM simply senses a fault and by design attempts a shutdown or derate. I am not an engineer but was a Boy Scout so shen the parts are available I will have one in the basement of our Entegra.

[Winepress]

Originally Posted by Dutch Star Don

Well, they keep talking about a chip shortage to fix this issue. It just amazes me that someone in this country can't duplicate the chip.

I was in the chip fab business in the past. Our capacity to manufacture chips in any large quantity is gone. 80% in Taiwan run by engineers educated here. Designed here manufactured there.

[Fiesta48]

I rarely get regeneration. Maybe once or twice a year in 7500 miles. I refuse to let my diesel idle for more than a couple of min. I also drive very conservatively. Minimize city driving.

[tom chelbana]

When we shut the engine down there is a pump that returns the DEF fluid in the lines back to the tank so the DEF fluid won't freeze in the line. When we do a Quick Start which is turning the key or pushing the button right away before the lights are off on the dash and the DEF fluid is pumped back in the lines could cause a sensor problem.
Keep the tank at 1/2 or more full would less then the tank level sensor from sending a false sensor reading on the level of DEF in the tank.
Insulating the DEF tank area along with using exhaust wrap when exhaust is close to the DEF tank should cut the temperature of DEF fluid which again should less the false sensor reading.
These 3 suggestions might not be the answer but at this point that is what we are doing until we are 100% sure what is the answer to all these DEF head problems.
Newmar Man

[ThunderRidge]

What I see from everything I have read on the different DEF topics seem to indicate none other than extremely poor engineering and the inability or completely unwillingness of the manufacturer and coach builders to get involved and demand the EPA allow the coach to operate normally until there is a solution to this problem.

For someone who has spent a considerable amount of money to purchase a coach and then be stranded in GOD knows where or to be without the use of this coach for months on end is unconscionable.

Perhaps we all need to get out in front of Spartan, Newmar, Entegra, Shaw, Freightliner, and all major dealers of these coaches with information to prospective buyers what kind of risk they are taking with these DEF heads. None of these entities seem to care at all. As long as they can continue to push their products off the production line and sell them off the dealers lots they are not going to get involved in the solution.