Going Into the Dreaded Diesel DEF Limp Mode

Truck Camper Adventure Switches to BlueDEF Platinum

Unfortunately, it happened. Our Ram 3500 Cummins 6.7L truck went into the dreaded “limp mode” on a recent trip here in Arizona. The alarm on the dashboard read, “5 mph Max Speed in 100 mi, Service DEF System, See Dealer.” If this has never happened to you, it sucks. Engineered to prevent further damage to your vehicle, the limp mode forces you to see a dealership because 5 mph isn’t a safe speed to drive anywhere, city or highway. It also forces you to sometimes call a tow truck. Fortunately, we were within 100 miles from our destination when we got the warning, so we were able to get it to a service center before it went into this so-called “protective” mode.

The news from the service center wasn’t good. The tech told us that our truck needed a new Diesel Exhaust Fluid (DEF) pump, a repair that would cost $1,797 ($480 in parts; $1,317 in labor). The code reader showed an error code of P208A, Redundant DEF Pump “A” Control Circuit Open. We also had a bad Bank 1 NOx sensor, which triggered another error code of P1C55, which we had already known about, but didn’t trigger the limp mode. This required a replacement as well costing another $1,650 ($1,410 parts; $240 labor). Ouch!

Apparently, these are common repairs for diesels with Selective Catalytic Reduction Systems (SCR’s) running DEF (basically all diesels built after 2010). This is because most DEF formulas leave harmful deposits that will eventually cause failures like ours (a bad—read old—batch of DEF can trigger a DEF limp mode as well). We were fortunate that our system lasted seven years before it had a major failure, but other diesel owners haven’t been so fortunate. Some have had to make similar repairs soon after their warranties expired.

Coincidentally, two weeks later the good folks at Old World Industries, the manufacturer of Peak Coolant and BlueDEF, contacted us about their new BlueDEF Platinum, a new formula that they claim significantly reduces harmful DEF deposits. If you have a diesel engine with a SCR system, you’re probably familiar with the filmy, white deposits left by DEF fluid if you’ve ever spilled it on your truck or on the ground. Imagine these white deposits in your DEF system building up over time, creating all sorts of problems. Having just forked out over $3,500 in expensive repairs, you’ll under understand why we were intrigued when we learned about this new product.

According to Old World Industries, BlueDEF Platinum is a mixture of high purity synthetic urea, deionized water, and a proprietary formulation featuring what the company calls its “Advanced System Shield Technology.” This refined formula, they say, significantly reduces harmful deposits that commonly build-up in modern diesel exhaust systems with SCR systems. These build ups, which are difficult to remove, can lead to back pressure, resulting in increased fuel consumption, as well as reduced engine power. Basically, these deposits are a result of the urea not burning-off completely. BlueDEF’s Platinum burns cleaner and reacts more completely in the exhaust system, which is how the deposits are reduced. It does so in the DEF injector itself, post DEF injector, and on the front of the SCR system.

BlueDEF Platinum, the company claims, is the purest DEF formula in the market. It is manufactured under ISO 22241 guidelines to ensure the highest product quality and is API registered, meeting or exceeding OEM specifications for diesel exhaust fluid. The MSRP for the new Platinum formula is $22.95, about $6 to $9 more than typical brands including regular BlueDEF.

Is using BlueDEF Platinum worth the extra cost? If it really works, we think so. Yes, we know what you’re thinking, “just delete all the emissions stuff and be done with it!” Well, with 74,000 miles now on our truck and our existing warranty, that isn’t an option. The warranty will be null and void if anything were to happen to the covered parts in a deleted engine. Unfortunately, our truck’s “warranty forever” warranty doesn’t cover emission DEF, SCR, and EGR related issues.

What brands DEF did we use before that created these costly deposits in our SCR system? Basically, whatever was available on our trips. We preferred using the regular BlueDEF formula, but that wasn’t always possible. When you’re on the road you don’t always have a choice when it comes to DEF. Some brands we used east of the Rockies we had never even heard of. All were supposedly ISO22241 compliant, but you have to wonder if some of these brands caused these costly deposits. And if all of these brands were compliant does the ISO standard need to be raised? Possibly. In the meantime, we will continue to use the BlueDEF’s Platinum grade in the hope it keeps our SCR system running cleaner and smoother.

To learn more about this intriguing new product, go to www.BlueDEFPlatinum.com.

About Mello Mike 878 Articles
Mello Mike is an Arizona native, author, and the founder of Truck Camper Adventure. He's been RV'ing since 2002, is a certified RVIA Level 1 RV Technician, and has restored several Airstream travel trailers. A communications expert and licensed ham radio operator (KK7TCA), he retired from the U.S. Navy in 2004 as a CWO3 after 24 years, holds a BS degree, and now runs Truck Camper Adventure full-time. He also does some RV consulting, repairs, and inspections on the side. He currently rolls in a 4WD Ram 3500 outfitted with a SherpTek truck bed with a Bundutec Roadrunner mounted on top.


  1. Mike
    Recently I had the check engine light come on. I took my 2500 Ram Laramie to the dealer. They replace the DEF System, Pump and Tank according to them. But they did it all under warranty. I’m sure glad it was covered under warranty.

  2. Many thanks for a Great heads up Mike!…Folks use to buy diesels because they were famous for their longevity, but unfortunately with all the emissions add ons, this is no longer the case, in fact one diesel fan fella I spoke to said he would only own a diesel so long as it was still under warranty – After tons of emission equipment issues on my previous 07.5 6.7 (first year 6.7) Cummins, I often reflect on his sage advice…In light of this, the switch to DEF does have it’s advantages mainly because it treats the NOx chemically, and mostly within the exhaust tract…

    Having said that, now at 55k mi on my 16 dually, I’ll be keeping a keen eye on fords new gasser – hopefully, they’ve overcome their dreaded stripped spark plug disasters that plagued their 5.4 and 4.6 V8’s…


  3. Holy Moly!! Sorry to hear that. We have a 6.7 PS and have an issue with the DEF sensors in the tank. Instead of giving us the “500 miles to empty” at half a gallon left, it would give us that message with 3 gallons left. A real pain. It’s random.
    Deleting isn’t all it’s cracked up to be. I did it and hated it so much, I had it re-installed. It’s load, smokey, and it makes the exhaust brake useless.

  4. Hi Mike,
    Ouch! Sorry to hear about your DEF pump failure. My RAM 3500 is a 2018 year, but pretty much the same Cummins Diesel engine, so I was concerned and did some research and talked to the folks at my RAM service department. The overwhelming conclusion was that DEF is DEF and that ALL DEF must adhere to the ISO 22241 standard. IF a product does not adhere to the ISO 22241 standards, then that fluid cannot by definition be called a Diesel Exhaust Fluid (DEF). The slightest amount of metals/contaminants found in the water or urea will cause the fluid to not meet the ISO 22241 specification. No disrespect intended here Mike and really love reading TCA, just don’t see any evidence to support BlueDef Platinum claims. They have a great marketing department though!!

    Kind Regards,
    Cheese Head

    • Yeah, I realize that, but they are claiming that this new formula exceeds the ISO standard and prevents harmful deposits. We’ll see. This article was written more as an informational post. Not everyone knows about this new formula. I didn’t.

  5. Mike,
    Thanks for the article and sorry for your troubles, especially since I own the same engine. I am uncomfortable with the different brands of DEF.

    I have been running generic brands with the required ISO 22241 and API certification. My reasoning is (1) it meets the manufacturer’s requirements at 1/2 the price of the premium brands such as Blue Def and (2) the premium brand has never offered me a shred of evidence that it is any better than the cheaper generic brand.

    If premium brands of DEF are truly better in quality, then they should offer evidence such as A/B photos of parts at 100k miles with less deposits or offer comparison of exhaust backpressure data as evidence. They can certainly provide evidence of a better product without revealing their formulation.

    I’d love to see an article with actual data on the benefits of the premium DEF. Any searches I’ve done the internet just come up with fluff.

    Best wishes on recovery to your wallet. CMack

    • I agree. Details on the formula and evidence of deposit reduction would be great. With it being so new, we’ll have to wait until the actual evidence comes in.

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