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My generator will not run for more than 58 seconds.  Mater of fact it runs every time for 58 seconds.  All the troubleshooting said to check the cooling level (it was good).  I decided to change out the coolant and add new coolant.  Changed the oil, air filter and fuel filter also.  Figured I'd do it all.  Same results, 58 seconds.  Didn't think that would change anything but it was almost due only 280 hours on the gen.  The next thing was the cooling sensor.  I removed the cooling sensor (what a pain in the butt).  Now I have a big problem.  The threaded portion came out (with a little muscle).  The bottom portion of the sensor didn't come out.  It is stuck in the opening.  There is all of about 2 or so inches to work with because the heat shield for the exhaust is right there.  I am on the road so I don't have the tools I would normally have but will buy whatever I need to get the gen fixed.  Any ideas on how to get the bottom piece of the sensor out (not much room to work with)???  Thanks in advance for any advice.

Don Genesse (namvet77)

04 Camelot

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What was the fault code you got each time it shut down?

When my Coolant Temperature Sensor failed the generator would run for almost 5 minutes before shutting down, like 4 minutes and 55 seconds. Plus the error code was #24.

I had the Cummins shop in Orlando replace the sensor and do complete service before heading out on a summer trip to the west back in 2017. Been running fine ever since.

58 seconds sound like something else is going on and not the Coolant Sensor.

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The housing for the sensor is behind the thermostat housing and I have to use a mirror to even see the hole where the sensor came out. Picture wouldn't show anything.  I'm going to see what it would take to remove the exhaust heat shield.  If I can get that out I will be able to see the hole and provide pics.


The PN for the sensor is 193-0318.  Bought it at the local Cummins dealer and paid $44.18.  Found it on the internet for $25 dollars.  Next time I'll know better.


Thanks for the link to others that have the same issue.  Doesn't sound like it's going to be an easy fix.  What really exacerbates the issue is I am in a campground in San Diego and I'm not supposed to be working on my motor home.  So far no one has said anything.  


The fault code was 33.  That supposedly identifies a cooling problem or a bad sensor.  I talked to a tech at the Cummins facility and he said the sensor is probably the problem as long as the fluid level was correct.  I just have to figure out how I'm going to get the rest of the sensor out so I can install the new one.  Maybe I'll try and find an authorize repair shop and pay the piper.  The Cummins shop is backlogged for the next month.  I still have 2  1/2 months left on this trip before I get home to Florida.  Once home I will have whatever I need to fix the problem.  Just don't want to wait until then.  The gen is on a slide out but still hard to get to with the exhaust shield in the way.

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Well that is weird because when I read through Fault Code 33 it says nothing about the Coolant Sensor failing causing Fault 33.  However, it does list a significant number of causes for High Coolant Temperature.

Now, if you had a Fault Code 24, that DOES specifically state the Coolant Sensor has failed not allowing the engine to run more than 5 minutes.

It just may end up to be completely different problem even after you figure out how to remove the broken sensor.

OR.....you could do the following

The manual also states that Fault 24 is a by-passable fault with exceptions as stated on page 18-1.

Refer to your manual for above information.

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Your not working on your motorhome, your working in the generator… gotta use the gray area wherever you can.

kidding aside.. your sensor is packed off with calcium type build up.  
what I did.

buy a right angle drill adapter for a drill (mine was 12” long)

buy a stubby drill bit the size of the sensor hole.  I’m not home to remember the name or size but I got it at Home Depot in the drill isle.  It’s not a “Chuck” type of bit.  It’s a hex type about 1.5” to 2” long is all.

I’m pretty sure they are counter sink type of hex bit.  It was a “Ryobi speed load bit).  Just can’t remember the size… I bought 2 of them.  Take the part you got removed and use it for size up.

remove t-stat from top of engine & remove coolant below sensor hole. Place rag below sensor hole.

two people - 1 to run the drill & 1 to run right angle head through sensor mounting hole.  

it takes a lot longer to prep the whole thing than it will to drill.  You are only drilling brass & the calcium. 

Hope this helps & good luck!

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On 7/30/2021 at 9:56 AM, Dr4Film said:

58 seconds sound like something else is going on and not the Coolant Sensor.

I tend to agree with Richard on this one.  58 seconds is hardly long enough for the coolant temp to rise much at all.  I know this is totally unrelated, but I have had similar problems with my 7500 generator--running a very short time and then shutting off.  In my case, it could always be cured by holding down the Start/Stop switch in the Stop position repeatedly for 30-60 seconds.  During that time, you can hear the fuel primer pump running.  That procedure is in the manual for the Onan.  It would normally apply only if you had changed fuel filters or done something to disconnect the fuel inlet plumbing.  But in my case, I've had to do this multiple times over the years when the genny knocked off.  Don't recall the error codes the first time it happened.  Now, I just know what to do to get it going again.  HTH.  Good luck!  Let us know how it turns out.

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Yea I noticed I put the original post in the wrong section.  It really hurts getting old!!  Your description sounds good.  I'll have to hit up HD to see what I can get.  I thought about cutting out a section of the exhaust heat shield and rivet it back in place.   That would be an easy fix if I was at home.  At least I have a drip pan to catch any coolant that leaks out.  I'll give it a try as soon as I get all the tools I need.  Thanks for the info.


When I talked to tech service at Cummins, they said if the sensor is shorted the system senses an overheat situation so it would only run for a minute.  I did change the fuel filter and before I tried to start the gen an primed it 5 times for 30 seconds. Then I tried to start it.  It ran great for 58 seconds.  Tried it several more times and same results.  That's when I decided to change the sensor.  Now I get to fix it.  YEA!!!!

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  • 1 month later...

Post is a bit dormant but the newest post on subject so I will add my experience. From a post on IRV2 that I no longer can find, the Gen control has a timer and checks for every thing to be good at a couple of time intervals. Thus the 55 seconds and close to 5 minute shut down. I got the 1/2" npt threaded section of my sensor out with the heat shield in place. 19mm socket and breaker bar to get loose, rachet to finish. the wire going into the sensor small diameter cylinder pulled out as the cylinder was stuck. tried going thru the thermostat opening with small pry bar to push cylinder out but no movement. Per another post, a hole saw was used to drill a 2" diameter hole in the heat shield to give access to the sensor bore. packed the thermostat housing with paper towels and ran a 3/8" drill into the cylinder. bit caught and spun the cylinder out. I expected the thru hole to be about the diameter of the cylinder. after picking away at the crystalized coolant, the hole is the drill diameter (approx) for the thread. vacuumed up all the crystals and installed the new sensor. Mine did not come with a new nut so keep the old one. JB Weld and the corner is now back in place. Some people are pulling their sensor every few years to keep the crystals from locking up the sensor. Another method was to chisel out a slot at one of the bolt holes of the housing that is blocked in place so the thermostat housing could be slide down and be rebuilt. if the threads in the aluminum housing strip out, that might be a good approach. Have 3 hours running since replacement to run cleaner thru system, flush and install coolant, the gen pulled 38 amps this morning with no shutdown. The JB weld is a bit sloppy but not many people will see it under the top panel.

HRS gen temp sensor hole.JPG

Edited by ok-rver
packet >>>> packed
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  • 2 months later...

Well it's been a couple months since I posted the problem with the generator.  As it turned out it was the sensor.  It was a bear of a job but got it done.  Cutting a hole in the exhaust heat was the best result.  Bought a piece of aluminum and epoxied it to the old cutout and drilled 4 holes in the aluminum to the heat shield to hold it in place.  The generator now works as advertised.  Thanks for all the feedback.

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