DC/DC converter
I'm not going to try and convince you that these types of failures aren't concerning - but I would really encourage those of you suffering these converter failures to put things in perspective. Especially when put in context of the wider automotive industry in 2026.
There is no perfectly reliable vehicle. Full stop. For the complexity and engineering involved in the L663, its remarkable how dependable it actually is. Yes there are common problems such as coolant consumption and leaks, and now it seems that we P400's might have a systemic issue with our exhaust manifold bolts. The converter failures may be one of these widespread issues.
These are still small potatoes compared to the issues that modern vehicles are experiencing all over the industry. GM Transmissions and engines exploding. Ford has suffered more recalls in the past few years than any other manufacturer, Stellantis has hybrids that cant be parked inside because they like to turn into a Car-be-que. The Euro brands have their own issues - for example, my 2019 Cayenne might have an issue where the V6 is making glitter in its oil because of poorly fitted pistons slapping the cylinder skirt. BMW, well... BMW. Then you have Toyota whose heretofore stellar reputation has suffered mightily with the 3.4L engine issues which are not going to go away. Hell, my old "reliable" diesel truck just had to have its engine rebuilt because one of the timing gears decided to leave the chat.
In the end, the Converter is something that appears to be replaceable in the driveway and while the part may be a bit pricey (when its available) this part going bad is not going to mechanically total the vehicle.
There is no perfectly reliable vehicle. Full stop. For the complexity and engineering involved in the L663, its remarkable how dependable it actually is. Yes there are common problems such as coolant consumption and leaks, and now it seems that we P400's might have a systemic issue with our exhaust manifold bolts. The converter failures may be one of these widespread issues.
These are still small potatoes compared to the issues that modern vehicles are experiencing all over the industry. GM Transmissions and engines exploding. Ford has suffered more recalls in the past few years than any other manufacturer, Stellantis has hybrids that cant be parked inside because they like to turn into a Car-be-que. The Euro brands have their own issues - for example, my 2019 Cayenne might have an issue where the V6 is making glitter in its oil because of poorly fitted pistons slapping the cylinder skirt. BMW, well... BMW. Then you have Toyota whose heretofore stellar reputation has suffered mightily with the 3.4L engine issues which are not going to go away. Hell, my old "reliable" diesel truck just had to have its engine rebuilt because one of the timing gears decided to leave the chat.
In the end, the Converter is something that appears to be replaceable in the driveway and while the part may be a bit pricey (when its available) this part going bad is not going to mechanically total the vehicle.
Drifting
Joined: Apr 2023
Posts: 25
Likes: 15
I'm not going to try and convince you that these types of failures aren't concerning - but I would really encourage those of you suffering these converter failures to put things in perspective. Especially when put in context of the wider automotive industry in 2026.
There is no perfectly reliable vehicle. Full stop. For the complexity and engineering involved in the L663, its remarkable how dependable it actually is. Yes there are common problems such as coolant consumption and leaks, and now it seems that we P400's might have a systemic issue with our exhaust manifold bolts. The converter failures may be one of these widespread issues.
These are still small potatoes compared to the issues that modern vehicles are experiencing all over the industry. GM Transmissions and engines exploding. Ford has suffered more recalls in the past few years than any other manufacturer, Stellantis has hybrids that cant be parked inside because they like to turn into a Car-be-que. The Euro brands have their own issues - for example, my 2019 Cayenne might have an issue where the V6 is making glitter in its oil because of poorly fitted pistons slapping the cylinder skirt. BMW, well... BMW. Then you have Toyota whose heretofore stellar reputation has suffered mightily with the 3.4L engine issues which are not going to go away. Hell, my old "reliable" diesel truck just had to have its engine rebuilt because one of the timing gears decided to leave the chat.
In the end, the Converter is something that appears to be replaceable in the driveway and while the part may be a bit pricey (when its available) this part going bad is not going to mechanically total the vehicle.
There is no perfectly reliable vehicle. Full stop. For the complexity and engineering involved in the L663, its remarkable how dependable it actually is. Yes there are common problems such as coolant consumption and leaks, and now it seems that we P400's might have a systemic issue with our exhaust manifold bolts. The converter failures may be one of these widespread issues.
These are still small potatoes compared to the issues that modern vehicles are experiencing all over the industry. GM Transmissions and engines exploding. Ford has suffered more recalls in the past few years than any other manufacturer, Stellantis has hybrids that cant be parked inside because they like to turn into a Car-be-que. The Euro brands have their own issues - for example, my 2019 Cayenne might have an issue where the V6 is making glitter in its oil because of poorly fitted pistons slapping the cylinder skirt. BMW, well... BMW. Then you have Toyota whose heretofore stellar reputation has suffered mightily with the 3.4L engine issues which are not going to go away. Hell, my old "reliable" diesel truck just had to have its engine rebuilt because one of the timing gears decided to leave the chat.
In the end, the Converter is something that appears to be replaceable in the driveway and while the part may be a bit pricey (when its available) this part going bad is not going to mechanically total the vehicle.
No vehicle is 100% reliable. But leaving your business customers stranded without a capable vehicle and no insight as to when you will get your vehicle back is totally unacceptable!
Last edited by Scandinavian outdoor; Mar 5, 2026 at 01:04 AM.
Rock Crawling
Joined: Sep 2017
Posts: 367
Likes: 169
From: South Florida
Sorry, but I REALLY have a hard time sharing your “perspective” here. I paid a small fortune for a commercial vehicle used in my small outdoor business. My Defender has my logos on it and is the visual identity of my business. I am very dependent on this vehicle for towing canoe trailers, bringing equipment, paddles, life vests, etc to my customers off the road / in the countryside. I have now been without my vehicle for 3 weeks - the loaner I got isn’t capable enough and doesn’t have a tow hitch - and JLR has absolutely “no idea” as to when I will get my vehicle back.
No vehicle is 100% reliable. But leaving your business customers stranded without a capable vehicle and no insight as to when you will get your vehicle back is totally unacceptable!
No vehicle is 100% reliable. But leaving your business customers stranded without a capable vehicle and no insight as to when you will get your vehicle back is totally unacceptable!
It’s true that issues like these are not uncommon these days and happen across brands (luxury or non-luxury) it seems, so not a specific JLR issue.
What seems to be more of a JLR issue is their inability to address these break downs in a timely manner due to lack of parts availability. One could understand that being an issue back in the COVID days (my D90 spent 3 months parked at a dealer in 2022 waiting for a part) but not in 2026. Is JLR’s Defender production line idle waiting for parts today? Probably not, so they are sourcing this part for new car production so how about balancing allocation between new car production and replacement parts to minimize impact to existing customers?
That to me is the area where JLR is failing and ultimately diminishing the brand.
Last edited by Juancl; Mar 5, 2026 at 12:47 PM.
Three Wheeling
Joined: Sep 2025
Posts: 72
Likes: 57
From: Down Under
Perhaps then Defender is not the right vehicle for you?
I would suggest perhaps your next vehicle of choice should be based on after-sales customer service rather then the vehicle qualities itself.
I would suggest perhaps your next vehicle of choice should be based on after-sales customer service rather then the vehicle qualities itself.
1st Gear
Joined: Mar 2026
Posts: 1
Likes: 1
Does anyone know if JLR has solved the DCDC converter issue in the newer 2026 models? I’m putting in an order for a P400 110 in a few weeks and logic would tell me they have identified the weak component (converter) and would have addressed it with their part supplier by now given how many cases this is causing
4wd Low
Joined: Mar 2025
Posts: 14
Likes: 8
From: Calgary, Alberta, Canada
Does anyone know if JLR has solved the DCDC converter issue in the newer 2026 models? I’m putting in an order for a P400 110 in a few weeks and logic would tell me they have identified the weak component (converter) and would have addressed it with their part supplier by now given how many cases this is causing
I would still personally recommend investing in a GapID tool and disabling the PTC heater, as a bit of insurance.
Three Wheeling
Joined: Oct 2021
Posts: 88
Likes: 44
From: Phoenix, AZ
Question regarding the PTC Heater - Living in AZ, I have actually never turned on the heater in my Defender - if the heater isn't ever used, would you still suggest disabling the PTC heater with the GAP Tool? If you never use the heater, is the DC/DC converter an issue? Thanks!
TReK
Joined: May 2021
Posts: 2,562
Likes: 3,626
From: Kirkland WA
If this heater was the issue, these DC-DC failures would be a feature from the start. 2020-2024 there were zero mentions of this issue. All of a sudden in late 2025, the issue explodes all over the user groups.
It's not adding up.
It's not adding up.
4wd Low
Joined: Mar 2025
Posts: 14
Likes: 8
From: Calgary, Alberta, Canada
It could have just taken that long for the DC converters to fatigue and fail at a rate that anyone noticed. Not sure if anyone has a grip on if the failures are occurring as much on new low-mileage vehicles, or if it's predominantly the older vehicles, like my 2022 with 100,000km.
According to my understanding, the PTC is the single largest electrical load on the 12V side. 50 – 60A at least. Disabling it will result in less power needing to cross the converter. As with most things, the less you use the converter, the longer it should last. Hopefully.
According to my understanding, the PTC is the single largest electrical load on the 12V side. 50 – 60A at least. Disabling it will result in less power needing to cross the converter. As with most things, the less you use the converter, the longer it should last. Hopefully.
TReK
Joined: May 2021
Posts: 2,562
Likes: 3,626
From: Kirkland WA
It could have just taken that long for the DC converters to fatigue and fail at a rate that anyone noticed. Not sure if anyone has a grip on if the failures are occurring as much on new low-mileage vehicles, or if it's predominantly the older vehicles, like my 2022 with 100,000km.
According to my understanding, the PTC is the single largest electrical load on the 12V side. 50 – 60A at least. Disabling it will result in less power needing to cross the converter. As with most things, the less you use the converter, the longer it should last. Hopefully.
According to my understanding, the PTC is the single largest electrical load on the 12V side. 50 – 60A at least. Disabling it will result in less power needing to cross the converter. As with most things, the less you use the converter, the longer it should last. Hopefully.