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J1939 fault code · Brakes and air

SPN 46: air supply pressure

Air system pressure. Type another SPN and FMI to check it.

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Fault code lookupJ1939 · 191 SPNs
PART · SPN 46air supply pressureFAILURE · FMI anyAny failure mode
Stop the machine

Air system pressure. Low air can set the spring brakes or leave you without service brakes.

  1. Stop and let the air build.
  2. Listen for leaks.
  3. Check the compressor governor and air dryer.
Full page for SPN 46 →

Paste the whole line if you like: "SPN 3251 FMI 0", "3251/0" or Deere's "003251.00". Plain-words guidance; the service manual wins.

1Use the toolType the SPN and FMI off the screen.
2Add your siteFree for one site and one camera. No card.
3Fault codes, plus what you needFault codes, plus machine hours and repair tickets

What SPN 46 means

Air system pressure. Low air can set the spring brakes or leave you without service brakes.

How urgent it is

Stop the machine. This one can wreck the engine or hurt someone. Shut down where it's safe.

What to check first

  1. Stop and let the air build.
  2. Listen for leaks.
  3. Check the compressor governor and air dryer.

Plain-words guidance for a foreman, not a repair procedure. Makers add their own codes and steps; the machine's service manual wins.

In the Dozer app · Fault codes

Next time, Dozer catches the code when it fires.

Plug a CAN logger into the machine's J1939 port, or connect the telematics you have. When a code fires, Dozer opens a repair ticket with the meaning, how urgent it is and what to check.

  • The code, the machine and its hours on one ticket
  • Severity sorted: keep working, plan a stop, or stop now
  • The mechanic gets the checklist before they drive out
  • Repeat codes on the same machine get flagged
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Fault codes in Dozer: EX-04 · SPN 3251 FMI 0 · plan a stop today LIVE EX-04 · SPN 3251 FMI 0 · plan a stop today

Photo is an AI-generated stand-in, not a customer site.

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Questions crews ask

What does SPN 46 mean?

Air system pressure. Low air can set the spring brakes or leave you without service brakes.

Can I keep running with SPN 46?

Stop the machine. Shut it down where it's safe and find the cause before you run it again. If the machine derates or the stop lamp is on, stop.

What should I check first for SPN 46?

Stop and let the air build. Listen for leaks. Check the compressor governor and air dryer.

How do I clear SPN 46?

Fix the cause first. Most codes go inactive by themselves once the condition is gone and the engine has run a key cycle or two. Clearing it with a service tool without a fix only hides it until it comes back.

Which machines show SPN 46?

Any diesel that speaks SAE J1939: excavators, dozers, loaders, haul trucks, generators and on-road trucks with Cat, Cummins, Deere, Komatsu, Volvo, Kubota, Perkins and other engines. The SPN means the same thing on all of them; the fix steps can differ, so check the service manual.

Related free tools

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