DOC Inlet Temperature Out of Range
The PACCAR-P1402 (PACCAR MX) diesel fault code means: DOC Inlet Temperature Out of Range. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- intermediate
- Estimated cost
- $600-$4,500
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View pilot availability →What Are the Symptoms of PACCAR-P1402?
- DPF warning lamp illuminated
- Engine derate (progressive stages)
- Frequent active regens requested
- Forced / parked regen required
- Reduced fuel economy
What Causes PACCAR-P1402? (Most Likely First)
- Plugged DPF from failed regens or short-haul duty cycle Likely
- HC doser injector coked / plugged Likely
- EGT sensor failure or wiring fault Possible
- Differential pressure sensor hoses clogged with soot Possible
- Upstream fuel / air / EGR fault preventing proper regen Possible
Can I Still Drive with PACCAR-P1402?
Short distances only. PACCAR-P1402 is rated moderate severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What does PACCAR MX code P1402 mean?
PACCAR MX code P1402 (DOC Inlet Temperature Out of Range) is a moderate-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 aftertreatment system that should be diagnosed with DAVIE4 or PACCAR ESA.
Can I drive a Kenworth or Peterbilt with PACCAR P1402?
Possibly — short distances may be OK, but ignoring the fault risks progressive damage, regen failure, or derate. Address promptly.
How much does it cost to fix PACCAR MX P1402?
Typical repair runs $600-$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-P1402?
Connect DAVIE4 and capture DPF soot load, ash load, and time since last successful regen.
Compare EGT sensor readings at idle — all should read within 20 degrees F of each other when cold.
Remove and inspect differential pressure sensor tubes for soot plugging; clear and reinstall.
Attempt a parked / service regen. If it fails or temperatures don't climb, inspect HC doser and DOC.
If soot load is below threshold but fault persists, DPF may be cracked / face-plugged — inspect or bake.
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)
P1402 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-P1402?
- 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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