Exhaust Temperature Sensor 1 Circuit
The PACCAR-P1424 (PACCAR MX) diesel fault code means: Exhaust Temperature Sensor 1 Circuit. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- intermediate
- Estimated cost
- $600-$4,500
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Common Symptoms
- DPF warning lamp illuminated
- Engine derate (progressive stages)
- Frequent active regens requested
- Forced / parked regen required
- Reduced fuel economy
Probable Causes (Ranked by Likelihood)
- 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
Step-by-Step Diagnostic Procedure
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.
Frequently Asked Questions
What does PACCAR MX code P1424 mean?
PACCAR MX code P1424 (Exhaust Temperature Sensor 1 Circuit) 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 P1424?
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 P1424?
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.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P1424 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown: