PACCAR-P1050 moderate PACCAR MX ›

Crankcase Breather Filter Restriction

The PACCAR-P1050 (PACCAR MX) diesel fault code means: Crankcase Breather Filter Restriction. This is a moderate severity code.

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Keep driving?
Short distances only
DIY difficulty
intermediate
Estimated cost
$500-$3,800
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What Are the Symptoms of PACCAR-P1050?

  • Loss of power or boost
  • Black or white smoke
  • Rough idle
  • Check Engine Light with possible derate
  • Failed or incomplete regen

What Causes PACCAR-P1050? (Most Likely First)

  • Failed actuator or position sensor Likely
  • Soot buildup in EGR valve or VGT vanes Likely
  • Vacuum or charge-air leak in boost system Possible
  • Wiring harness rub-through near turbo heat shield Possible
  • EGR cooler internal leak or clog Less Likely

Can I Still Drive with PACCAR-P1050?

Short distances only. PACCAR-P1050 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 P1050 mean?

PACCAR MX code P1050 (Crankcase Breather Filter Restriction) 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 air system that should be diagnosed with DAVIE4 or PACCAR ESA.

Can I drive a Kenworth or Peterbilt with PACCAR P1050?

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 P1050?

Typical repair runs $500-$3,800. 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-P1050?

  1. Connect DAVIE4 and monitor VGT commanded vs actual position at idle and under load.

  2. Inspect charge-air piping clamps, hoses, and CAC for leaks — pressurize and listen.

  3. Remove EGR valve and inspect for soot lockup; clean or replace as needed.

  4. Check actuator harness for chafing on turbo heat shield or exhaust stud.

  5. Verify EGR cooler coolant flow and test for internal leaks (bubble test).

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)

P1050 on Other Platforms

The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown:

Gas / Automotive (OBD-II) Generic OBD-II definition for P1050

Which Vehicles Commonly Get PACCAR-P1050?

  • 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

Explore More

More PACCAR MX codes → Diesel home All diesel codes Heavy-duty Guides

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