Espar cabin heater not working in cold temps

We're in Banff Canada where the temperatures have ranged from 26F to -5F over the past 5 days. Yesterday our espar cabin heater stopped working. We plugged in an Autel-AutoLink A319 code reader and the code is as below.

Stored 1/1
P0100 $12 Generic
================= ======
Mass or Volume Air Flow

A Circuit

Does anyone know if this code is related to the espar cabin heater? Underneath the van we noticed a short piece of accordion hose that has a small 3-5mm hole in it. It seems logical that it could affect the airflow and therefore the duct flow if that hose is part of the espar ducting. See attached photo.

Any suggestions for getting the cabin heater back on line? We have 7/8 tank full of diesel, house batteries fully charged and we're plugged into electricity at a campground. Thanks



2004 T1N Westfalia
I'm confused.

Is the Autel-Autolink plugged into the cabin Espar heater?

If plugged into the OBDII port under dashboard, am almost 100% certain that the cabin Espar heater is NOT readable from that port.

BUT, the engine Espar heater (under driver headlight) may be readable from that OBDII port. Don't remember.
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Thanks onemanvan for the trouble shooting guide. Using the guide, the heater does nothing. It doesn't smoke, no noise or sign of life. We checked the fuse, it still looked good but we replaced it anyway, still no change.

OldWest, we plugged the Autel AutoLink into the port up under the left hand dashboard --not into the cabin espar cabin or the engine espar.

According to our Westy manual, on pg 11.9, "the integrated control unit of each auxillary heater contains a diagnostic system which detects and stores faults. The error can be read by means of the vehicle diagnosis." Based on that sentence, we plugged in the Autel reader under the dash to see if it would report anything useful. We don't know what that code means and if it's related or not to the function of the cabin espar heater.

Based on your comments, can we plug the reader directly into the cabin espar heater, and if so, how do we do that?

Can we physically examine the espar in place? What should we look for or what could we check?


2004 T1N Westfalia
Presumably, you have an original Espar heater with an original ECU Electronic Control Unit which can communicate with the windshield central computer console.

Westfalia has a unique Espar electronic control unit which can communicafe with the windshield central computer console. Westfalia also uses (spliced in) a different wiring loom and connectors. So regular Espar diagnostic folks will NEED an adapter to conmect to tbe Westfalia wiring (see below).

You may have a "lockout" where Espar has shutdown and needs to be reset with a diagnostic device like EDITH software or a Digi-Max or some other Espar device.

Diagnostic Options:

1. Windshield Central Computer Console

By pressing a series of buttons, you can get information about the Espar heater. See the repair manual CD (pdf is at

2. EDITH Software

Put onto a computer to read Espar.heater. Will need wiring adapter. Airstream uses this as welll as ThermoKing dealers.

3. Digi-Max

A standalome controller which can also do some diagostics. OneManVan posted some info on whether it might work which is dependent on when heater was manufactured.

4. Other Espar Controllers

There may be other Espar devices.

5. Practical

Without a diagnostic scan, can also do troubleshooting as in OneManVan's pdf above.

6. Replacement

Remember that any replacememt will NOT be compatible with the windshield central computer console and will NEED a new standalone control unit.

The good news is that Espar has a newer better? version out.

Please post whatever you find and do. Thanks.

Some other threads below.





'05 Westy
I also recall there being a Washington state location that worked on Espars. I might be wrong though. I would have read about it on this forum however.

Also, the code read by your scanner, you should clear it, drive the van a bit, and then recheck to see if the code reappears. If so, there is something with the engines mass flow sensor that might need attention. Usually searching the codes on the T1N forum will provide additional info.
Awesome feedback from all!

I was able to use the Westfalia repair manual to find out how to use the control center console to get a diagnostic test on the heater - attached is the result - it indicates the heater is only getting 0.1 Amps, not the 16-20 the manual says should be reported.

Just spoke to ThermoKing Calgary, and they said its likely the fan or pump. Matt sounded very familiar with this espar (older D4S). We're headed there now!



Active member
The fact that the heater is only drawing .1 amp current only tells you that the heater isn't doing anything - which you already new...

However "doing nothing" is a subjective description... For example if there is a lot of ambient noise - engine running, stereo blasting music, hearing impairment, etc... - then you might easily assume the heater is doing nothing.

The first thing you should hear is the relay inside the heater click ( you might need to put your ear up close to the heater to hear this ).

The second thing you should hear is the fan spool up ( maybe only briefly ).

The third thing you should hear ( after about a minute or two ) is the dosing pump begin clicking.

If you hear any of these things then the heater "is doing something".

The most common problem with the Westy heaters when they "do nothing" is an over temp lockout. To correct this issue you need to reset the heater ECU with a diagnostic tool.

However - you need to ask yourself WHY the ECU generated 3 or more over temp errors?
Most commonly it due to user error - IE: one or more of the heater outlet vents were closed/blocked OR the heater return air ducting is blocked/clogged. So if during your "COLD WEATHER" usage the heater inexplicably shutdown a few times and you were subsequently able to restart it that would be evidence the heater might have "locked out" due to "over temp faults".

Most Espar dealers have never dealt with the Westy specific wiring and connectors. Typically the first time they see a Westy heater installation they just scratch their head :thinking:

To interface any diagnostic tool with the Westy you need a custom made adapter.

If the Espar service tech is very competent they may be able to cobble together something to overcome the issue of unfamiliar connectors, maybe...
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New member
And as for the hole in the 'accordion hose': it needs to be there!

In fact, when I replace that hose I had to punch said hole into it manually.

I was told this is for any condensation to be able to escape.


2004 T1N Westfalia

So what happened? What was the solution? Where's the ending? Happily ever after?

So sorry for such a long delay in responding. Thanks to OldWest and Onemanvan for your help. This is how the saga went for us back in March:
Thermo King in Calgary had experience with espar heaters but after a 2 hr wait, they said they’d never seen a van and heater like ours and their code readers couldn’t interpret the problem. Later that day, we found a Mercedes dealer who had 2 Sprinter techs but they weren’t familiar with the older version of our Espar cabin heater. We then called our Mercedes mechanic at home (Portland, OR). He was confident that the Mercedes factory lap top would successfully read codes from our Espar cabin heater, so over the phone the 2 techs worked together and were able to identify the code and reset the heater. It had locked itself out from overheating (we now think d/t no high altitude adjustment capability).

Since we had been in -5F to 28 degree temps for 3 days w/o cabin heat, our grey and black water valves both froze and we were unable to dump the contents. We were able to locate an RV service center in Calgary that had a shop large enough to put the Westy inside overnight to thaw the pipes/valves. They also advised putting 2 gallons of antifreeze down the toilet and 3 in the sinks (we put 2 in the kitchen, and 1 in the bathroom). The next morning after the Westy had been inside for 16 hrs, the pipes all drained and gratefully w/o any sign of leaking or damage to the pipes/hoses. If you are ever in Calgary, and need assistance, go to Canadian Leisure RV. Mark (owner) was very helpful and knowledgeable and was the only shop that was willing to put the Westy inside for the night. We then continued on our trip to Montana, Wyoming, Colorado and back to the NW.

Recently, at the ThermoKing in Fairview, OR, we had them replace our D4 heater with the newer Airtronic S2 D2L and an Easy Start controller. I've attached PDF files if anyone is interested. The Airtronic 2 includes an integrated air pressure sensor with automatic altitude adjustment up to 3000 m. The install was a bit pricey ($1994 total) but we hope well worth it for further high elevation, cold weather trips to avoid the delays and problems we experienced this trip. The Easy Start controller also permits the user to read codes and clear them which we were not able to do on the universal controller in our Westy. It is about the size of a cell phone and communicates with an app on our phone so we can control the heater remotely also.

We won't be testing it out until next winter so will post an update then. Thanks again for everyone's help!



2004 T1N Westfalia
Thanks for the update!

Couple of things of interest.

1. The heater should probably be used at least once a month. Don't remember where but I think some owner manual recommends that.

I think this is a common recommendation for just about everything--generator, air conditioner, etc. Perhaps so things don't get corroded, stuck, etc.

2. The new heater has a smaller output than the old heater. This is good to prevent running at lower speeds where there would be more buildup in the combustion chamber.

Seems most Sprinter DIY campers find the smaller heater works for the various size Sprinters with various levels of insulation.

Also, the smaller heater should be able to keep up in our Westies, but please keep us posted.

3. The older heater was designed for the long ductwork with three outlets. The new smaller heater may have issues with the longer ductwork and turn off automatically. A quick fix is to disconnect the longer ductwork and just use one outlet. Please let us know if there are any issues.

4. The new smaller heater is not the same size as the older heater. The installers probably had to modify the metal steel enclosure box to elevate the new heater inside the box and may have extended the ducts. If you know or have photos, that'd be great.

Thanks for the update and info re ThermoKing.


2004 T1N Westfalia
Oh, forgot to ask. Where did you put the controller?

As you indicates that you can control remotely with a phone, that might make for an easier installation. Don't have to run wires to upper bunk but can control with phone.


'05 Westy
One thing to note that interests me is the MB dealer was able to reset the Westy cabin Espar This means that likely an MB-II OBD device as posted in another thread can indeed be used to reset the unit if needed. Great info!
Good feedback, OldWest. I've put a monthly reminder on my phone to run the heater and generator. We'll have to see next winter if the longer ductwork is an issue. TK did have to use a reducer to adapt the new heater to our ducting. I will call TK tomorrow to see how they did the install inside the box and ask for photos. They installed the controller above the window just behind the driver seat so they could run the wires up the narrow panel just behind the seat. (see attached photo). There is an indentation there which is a perfect fit for the new controller.


I spoke to ThermoKing today and they said there is a mount on the inside of the heater box on the bottom and they installed the new heater pretty much where the old one was installed. They didn't think that the longer ducting would be an issue but said to let them know if we had any questions or concerns. No photos of the install available.


2004 T1N Westfalia
Thanks. The smaller heater is not as high as the original but perhaps the ducts flex a bit inside the metal box.

Air Intake: The air intake is a hole in the floor under the front-most circular outlet near driver seat A pillar. Beneath the hole is a duct or hose which goes to the front of the metal box (toward front bumper).

Air Outlets: The air outlet is from the rear of the metal box. The duct comes from the rear of the metal box and then up to the floor next to the bench seat. The duct then splits into two ducts going in two directions: one duct goes toward the front circular outlet near driver seat A pillar, and the other duct heads to underneath the kitchen cabinet.

Under the kitchen cabinet, the duct then splits to the outlet under the kitchen cabinet and to the outlet in the bathroom wall.

Rearranging Ducts for Smaller Heater: If the smaller heater cannot handle the long ductwork and three outlets, I'd probably do something like this.

The only air outlet should be the one under the kitchen cabinet. This would allow the heat to rise up to the upper bunk. The outlet to the bathroom can be disconnected under the kitchen cabinet and the Y connector replaced with a straight connector. The duct to the bathroom can be left in place.

The duct to the front outlet should be removed and the T connector replaced with a straight connector to the kitchen outlet.

By removing the duct to the front outlet, you remove the potential issue where the duct droops and blocks the air intake on the floor. In addition, by removing the duct, the front outlet then becomes an air intake for the hole in the floor.

If any of the above is wrong, please correct.


2004 T1N Westfalia
A 1995 James Cook owner is installing an Autoterm D2 heater. This is the successor to the Planar D2 heater which looks exactly like an Espar D2. Autoterm/Planar is a Russian based company. The primary advantage of their clones is the much cheaper price.

The 1995 James Cook has a different older model Espar heater. Here's the link to the James Cook Forum thread. Some James Cooks apparently mounted the diesel pump inside the steel box. This poster made a new attached box. Our Westies have the diesel pump mounted outside the box without a container (note: OneManVan moved his diesel pump closer to the diesel tank outlet).


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