The Paccar MX ECM failures we see most

These show up across these ECMs week in and week out. If your symptom is on this list, that is good news. It means we have seen it before and it is fixable.

Injector driver failure

What you see: a dead hole, misfire, derate, or a rough run that follows the ECM and not the injector.

What's happening: the circuit that fires the injectors has burned or shorted, often paired with an internal power-supply fault on the MX PCI.

What we do: we rebuild that section of the board and bench-test every injector channel before it ships back.

No-start, unit dead, no communication

What you see: the ECM will not talk to your diagnostic tool, or the truck will not wake the engine at all.

What's happening: internal power-supply damage inside the PCI module, so the board will not boot or hold communication.

What we do: we restore the power section on the bench so it boots and communicates again, and the no-start clears.

Blown fuses and internal shorts

What you see: a unit that repeatedly pops a fuse, shows burnt components, or cuts out once it heats up.

What's happening: a short or a thermally-stressed component inside the module, sometimes from heat and vibration cracking a joint.

What we do: we find the shorted or cracked part, repair it at the component level, and heat-soak and bench-test the unit before it ships.

Don't see your exact symptom? Send it in anyway. These are the common ones, but these ECMs fail in other ways too, and we test every unit before we tell you what is going on.

How a Paccar MX ECM repair goes

  1. 1

    Ship it in

    Self-ship free, or add a prepaid UPS label. Drop-offs in Princeton, MN by appointment.

  2. 2

    We test it

    $350 bench fee, credited toward the repair. We test it and tell you exactly what failed, usually in 1-2 business days.

  3. 3

    We fix it

    Injector driver repair, power-supply restoration, component-level short repair, whatever it needs. Standard turnaround 3-5 days on the bench.

  4. 4

    Back to you

    Programmed to your engine, bench-tested, and backed by our repair warranty. Plus 1-3 days return shipping.

Verified Google reviews

What truck owners & shops say

★★★★★
"Mike does great work and sent my repaired ECM back to me right away. Saved me thousands of dollars vs. using the dealer. Would recommend to anyone that needs prompt repair."
Michael B. via Google
★★★★★
"From ECMs and harnesses to straight-out cutting counter bores in-frame for us. Great shop — and a great person to have in your pocket."
Mega24v via Google
★★★★★
"Highly recommend these guys! Fast turnaround — I had my ECM back and repaired by the next day. Will definitely do more business in the near future."
Javon Z. via Google
★★★★★
"Michael is a diesel guru. He made my rig scream and had it done when he said, for the price we agreed to. I'd highly recommend him."
Glenn S. via Google
★★★★★
"Mike is highly knowledgeable in all areas of diesel repair — from mechanical work to advanced electrical diagnostics. You can count on him to get the job done right."
David F. via Google
★★★★★
"Mike is a very professional and skilled mechanic. I highly recommend him for any of your needs."
Justin N. via Google

Read more reviews & leave your own →

Email us about a problem unit.

It comes straight to our inbox. A diesel tech reads it and answers, usually the same business day. Tell us the engine and what it's doing, and we'll let you know whether we can help.

Email us [email protected]

Send a quick question

Two fields. Goes to our inbox; we reply by email.