M135x red warning light, incorrect temp reading

Amaranthian450

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Equipment
Many Kubota tractors, haying equipment, seeding equipment
Jul 9, 2026
3
0
1
Manitoba
I have a 2012 kubota m135x and recently the red engine warning light to the left of the temp gauge has been illuminated with no real symptoms, checked all fluids, all good, new engine oil and filter and a new fuel filter have been installed and changed nothing,been running like this for about a week, until today when it seems to have thrown itself into limp mode. Tractor barely wants to move itself. And temp gauge seems to be incorrectly reading, after sitting all night I turn on the key and the gauge immediately comes up to normal operating temp even though engine is cold, and also glow plugs want to cycle before startup every time even with engine warm. What the heck is going on with this thing?
 

TheOldHokie

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L3901/LA525, G2160/RCK60, G2460/RCK60
Apr 6, 2021
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windyridgefarm.us
I have a 2012 kubota m135x and recently the red engine warning light to the left of the temp gauge has been illuminated with no real symptoms, checked all fluids, all good, new engine oil and filter and a new fuel filter have been installed and changed nothing,been running like this for about a week, until today when it seems to have thrown itself into limp mode. Tractor barely wants to move itself. And temp gauge seems to be incorrectly reading, after sitting all night I turn on the key and the gauge immediately comes up to normal operating temp even though engine is cold, and also glow plugs want to cycle before startup every time even with engine warm. What the heck is going on with this thing?
Its foobared.

Its going to take more than a broad question like that tossed out on OTT to figure out how. The first place to start would be the Owners and Workshop manuals. Like what does that engine warning light mean?

Dan
 

Amaranthian450

New member

Equipment
Many Kubota tractors, haying equipment, seeding equipment
Jul 9, 2026
3
0
1
Manitoba
Its foobared.

Its going to take more than a broad question like that tossed out on OTT to figure out how. The first place to start would be the Owners and Workshop manuals. Like what does that engine warning light mean?

Dan
If I had all the answers and workshop manuals I likely wouldn’t be on this site would I? Maybe somebody can actually tell me what that warning light means but it seems not many people know much about these tractors which is what worries me. If you want more info, air filters can clean, fuel is clean and it getting lots of it to the injection pump. When I first start the tractor it revs normals if I hit the throttle but after about 4 seconds the revs are limited and power is down. Some kind of electrical malfunction it seems like to me throwing it into limp
 

TheOldHokie

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Lifetime Member

Equipment
L3901/LA525, G2160/RCK60, G2460/RCK60
Apr 6, 2021
12,470
7,104
113
Myersville, MD
windyridgefarm.us
If I had all the answers and workshop manuals I likely wouldn’t be on this site would I? Maybe somebody can actually tell me what that warning light means but it seems not many people know much about these tractors which is what worries me. If you want more info, air filters can clean, fuel is clean and it getting lots of it to the injection pump. When I first start the tractor it revs normals if I hit the throttle but after about 4 seconds the revs are limited and power is down. Some kind of electrical malfunction it seems like to me throwing it into limp
Like I said - you are not goung to get your answers here. They are going to come from the owners and shop manuals. Start by finding out what the warning light you ignored means and how to trouble shoot it



Dan
 
Last edited:

North Idaho Wolfman

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Jun 9, 2013
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Sandpoint, ID
Sounds like you have an issue with one of the temp sending units.
More likely it will be #50, but #10 is also a temp sending unit.
The sending units will tell the glow plugs when they should work and not, that would be the reason for the odd glow plug cycle times.

I don't have the WSM for that model, but if you have a local Kubota dealer walk in with a USB key / thumb drive and ask if you can get a copy, some will give it too you, some will sell it to you.

This will tell you how to test the circuit and how it reset the limp mode if you can.
Some events require a Kubota computer to reset the system, If your in a farming area the local dealer probably will have the ability and service to do it on site. 1783701397883.png