Engine ECM Software Calibration Incompatibility
The PACCAR-P1004 (PACCAR MX) diesel fault code means: Engine ECM Software Calibration Incompatibility. This is a serious severity code.
Unverified. We could not confirm this code's definition against freely available manufacturer documentation, so treat the meaning, severity and fix guidance on this page as unconfirmed. Check it against the manufacturer's service information for your exact model and serial range before acting on it. This page is kept out of search engines for that reason, and we are working through this family manual by manual.
- Keep driving?
- No — stop driving
- DIY difficulty
- advanced
- Estimated cost
- $1,800-$4,500
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View pilot availability →What Are the Symptoms of PACCAR-P1004?
- Check Engine Light illuminated
- Possible no-start or stalling
- Scan tool communication loss
- Engine derate or limp mode
What Causes PACCAR-P1004? (Most Likely First)
- ECM internal hardware fault Likely
- Software corruption requiring reflash Likely
- Power or ground circuit issue Possible
- Low battery voltage during key-on Possible
Can I Still Drive with PACCAR-P1004?
No — stop driving. PACCAR-P1004 is rated serious severity. Continuing to drive in this state risks further damage — get it looked at before your next trip.
Frequently Asked Questions
What does PACCAR MX code P1004 mean?
PACCAR MX code P1004 (Engine ECM Software Calibration Incompatibility) is a serious-severity diagnostic trouble code set by the engine or aftertreatment control module on MX-11 and MX-13 engines in Kenworth and Peterbilt trucks. It indicates a fault in the engine control system that should be diagnosed with DAVIE4 or PACCAR ESA.
Can I drive a Kenworth or Peterbilt with PACCAR P1004?
No — this fault typically triggers engine derate or forced shutdown countdown. Continuing to operate risks further damage or a stranded truck.
How much does it cost to fix PACCAR MX P1004?
Typical repair runs $1,800-$4,500. Sensor or wiring repairs are at the low end; injector, DEF pump, DPF, or EGR cooler jobs are at the high end. Dealer-level DAVIE4 software is often required for programming or calibration after parts replacement.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose PACCAR-P1004?
Connect DAVIE4 or PACCAR ESA and confirm P1004 is active with freeze frame data.
Measure ECM supply voltage at pin — must be battery voltage key-on and stable during cranking.
Inspect ECM grounds at frame rail for clean, corrosion-free connections.
Check for PACCAR calibration updates and reflash if available.
If fault persists after reflash and wiring checks, ECM replacement with DAVIE4 programming is required.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J1939-73Application Layer: Diagnostics (defines the SPN/FMI fault-identifier framework)
P1004 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown:
Which Vehicles Commonly Get PACCAR-P1004?
- Kenworth T680 with PACCAR MX-13
- Kenworth T880 with PACCAR MX-13
- Kenworth W990 with PACCAR MX-13
- Peterbilt 579 with PACCAR MX-13
- Peterbilt 389 with PACCAR MX-13
- Peterbilt 567 with PACCAR MX-13
- Kenworth T440 with PACCAR MX-11
- Kenworth T470 with PACCAR MX-11
- Peterbilt 520 with PACCAR MX-11
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