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November 2025 by John Fowler
Been having various fault codes having to do with DEF Aftertreatment. Then engine power was derated. Made an appointment at Cummins Sumner. Brought it in for the appt and the fault was quickly diagnosed. When the part arrived, Jennifer worked my rig back into the shop schedule. Cummins Sumner was one of the best repair services I have experienced with this RV. The only delay was waiting for the part. Jennifer kept me advised on status along the way. I would not hesitate to use Cummins Sumner again, nor to recommend them to others. We'll done.
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September 2025 by Chris Millet
I brought in my RV with Onan gen to have diagnosed by Cummins. As a full time RVer with pets, we had to make Airbnb arrangements for expected 1-2+ day service so this is not trivial for us to do. Issue: Gen had a high temp shutdown and then became unresponsive. I suspected the control board in the inverter had fried, but wanted the pros to diagnose. Within an hour, they had come back with a $5k parts + $2k labor quote to remove the generator from the RV and replace the inverter. I asked if they could simply remove the inverter using the slide out tray the gen is mounted on and give it to me so I could have it rebuilt on my own for far less $. They said this was not possible and stood by their original estimate. I opted to have them return the RV. I'm an IT guy with beginner mechanic skills and using service manual I was able to remove the inverter in about two hours using the service manual as my guide. Really disappointed in Cummins. (picture provided as proof)
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September 2025 by Ricky
It would be nice if I could call the store and talk to somebody in the store instead of a call center! You guys are an absolute nightmare to deal with now.
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September 2025 by K L
The only positive thing I can say is that they have a good after hours drop off process and were able to look at our RV generator earlier than our scheduled appointment. Other than that, run away from Cummins Sumner as fast as you can.
Our RV is only 3 years old, and the generator stopped working recently despite just over 200 hours of use and regular maintenance. I thought taking it to Cummins was the best idea given they are the manufacturer and surely could be trusted with a quality repair at a reasonable price. I was wrong. I should have asked the cost to diagnose and since I dropped it after hours, assumed they would call and let me know the estimate. Instead, I get an e-mail that says the belt broke (a $37 part) but it would cost $2,500 to fix it. We pleaded with them to split the cost with us given the service history and age (feeling like faulty belt / COVID manufacturing issue) but they would not budge. So we said we'd pick it up and take it elsewhere. To our shock, before they would release it to us, we were told we owed them $580 for the diagnosis!
We called our mechanic friend who said he could fix it, and he said the $580 was ridiculous as the belt fragments could be seen by simply opening the generator compartment. We felt totally ripped off. We strongly encourage people to avoid this business.
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August 2025 by Todd Miller
I scheduled an appointment almost a month in advance. I took my motorhome in to have repairs done and was told they couldn't start on it for almost a week, because they had an emergency vehicle that needed to get done. I told them I needed it back in 3 weeks and they said it shouldn't be a problem. They charged a $650 diagnostic fee. It seems they couldn't locate the exact problem because they replaced both the lift pump and the fuel injection pump. I also had a cracked exhaust manifold and they said it was leaking oil and needed a new oil seal. all total $23,000. I have never noticed any leaking oil or had to add oil. I was told I could probably still get it back before my scheduled trip, depending on parts. Then I was told another emergency vehicle bumped me and I would not be able to pick up the vehicle until after my trip was over. I could go on and on, but I finally got it back. it was 4 weeks late which was still a week later than the last promise date they gave me. Never again.
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July 2025 by Mike Keller
Absolutly amazing staff. Garbage automated system.
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July 2025 by Avtar Singh Dhillon
Good experience.
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January 2025 by Duckwacker
Management needs to remind drivers when they have to legally stop for school buses dropping off students. Your driver illegally stopped and blocked Spanaway loop road stopping for a bus in the far north bound lane. We were heading south. It's a 4 lane road nobody heading south is required to stop. His plate number is C389053S.
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November 2024 by David Bevan
After major wind storm knocked out power in many large areas of Western Washington we used our motorhome generator for 4 days straight. Its oil got down to point it was next to nothing. We were in panic mode. Could not find correct oil anywhere but at Cummins. They luckily had power and were open. Sadly I did not get name of man I met there. He heard my story got two quarts of oil and a Cummins Hat. I asked how much. His response was Happy Thanks Giving and just handed to me. How can I not think well of them?
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October 2024 by Child of God
At Cummins, these guys really do you right. I took my old Kenworth semi truck in to have an overhead done. They were fast, helpful with my questions and did a great job on my old boy. Thank you Cummins! You guys rock! I will definitely be back. Good prices, great service and awesome people.
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October 2024 by Katherine Ford
At Cummins, these guys really do you right. I took my old Kenworth semi truck in to have an overhead done. They were fast, helpful with my questions and did a great job on my old boy. Thank you Cummins! You guys rock! I will definitely be back. Good prices, great service and awesome people.
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October 2024 by Bridget Allen
#CumminsDiesel is out of their minds.
First they bump us on our service appointment, which we arrived on time to, because a much larger account has a repair brought in a day AFTER ours and well, it's more money. That service is terrible. I hope it costs them to lose money. I hope karma finds you wanting and delivers a full-throated response.
Then they charge us $1400 to change a spark plug and apparently pay for more schooling of their tech because it seems he has class to go to.....not even making that up.
We dropped the truck with cab-over camper at the location in Sumner, WA 3ish weeks ago. That leaves me with zero ways to get hay, move horses, pull trailers, drive my truck, and in general, pull equipment, etc.
Now, they are saying they may or may not be able to find parts (the generator has been used 2 times) and then it'll cost us nearly $6000 to continue fixing it. I can buy a replacement generator for less.
Do not EVER trust a Cummins Diesel outfit. They will rob you blind and then say you are welcome. They have lost my business for a lifetime.
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October 2024 by Natalie Rager
Jennifer in the service department is very rude. Not only has she upset her customer, but now she has also lost a big part of the business that could have potentially be sent to there way.
Showing compassion is had to find these days, and you will defiantly not find it in the service department at Cummins Sumner with people like her.
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August 2024 by Peter Shelley
Thank you, Ashley and Jerell. . I’m getting ready to go to BurningMan and my RV Onan 4000 watt generator would not start. I’ve even been good running it monthly. I called several RV dealers that I’ve used before and Camping World and no one could see me for about six weeks. I called Cummins and explained my situation.
Ashley scheduled an appointment in two weeks but told me if I could bring it down earlier there was a possibility it could be looked at. That’s exactly what happened. It was fixed five days before it was scheduled to be looked at. And for only 2/3 of the estimate for the diagnosis. Thank you again. You saved the marriage!
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August 2024 by Jon Winslow
God bless Jennifer and Ray at this Onan dealer, they are amazing!! We were traveling across the country from Virginia when our generator went out. While I was trying to work on it I had an aortic aneurysm and had to go to the hospital. When I got out our RV was over 100 degrees. I called and Jennifer who got us an appointment with Ray, the technician. Jennifer efficiently completed our paperwork and made us and our 120lb. dog feel welcome and comfortable! Ray juggled his extremely busy schedule to repair our generator in between other appointments! We are forever grateful to them and they are they kind of employees who uplift the Onan company name and keep the corporate reputaion held in high regard!
