Fuel Rail Pressure Sensor Circuit Range/Performance
The PACCAR-P0191 (PACCAR MX) diesel fault code means: Fuel Rail Pressure Sensor Circuit Range/Performance. This is a serious severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- intermediate
- Estimated cost
- $300-$3,500
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View pilot availability →What Are the Symptoms of PACCAR-P0191?
- Check Engine Light illuminated
- Performance loss or engine derate
- Rough idle, hard starting, or stalling
- Scan tool communication issues (U-codes)
- Possible smoke or unusual noise
What Causes PACCAR-P0191? (Most Likely First)
- Sensor or actuator failure in the affected circuit Likely
- Wiring harness damage, chafing, or corrosion Likely
- Contaminated fuel / DEF / coolant Possible
- ECM or CEM needs reflash for known calibration issue Possible
- Mechanical wear (high-mileage truck) Possible
Can I Still Drive with PACCAR-P0191?
Short distances only. PACCAR-P0191 is rated serious severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What does PACCAR MX code P0191 mean?
PACCAR MX code P0191 (Fuel Rail Pressure Sensor Circuit Range/Performance) 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 fuel system that should be diagnosed with DAVIE4 or PACCAR ESA.
Can I drive a Kenworth or Peterbilt with PACCAR P0191?
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 P0191?
Typical repair runs $300-$3,500. 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-P0191?
Pull all active and inactive codes from ECM, CEM, ABS, and TCM with DAVIE4 — root cause often sets multiple codes.
Capture freeze frame data and compare values to known good operating ranges.
Back-probe the affected sensor / actuator circuit with a DMM key-on engine-off and running.
Inspect wiring harness at valve cover, turbo, and frame crossover points for chafing / rub-through.
After repair, clear codes and perform a road-test drive cycle to verify fault does not return.
Sources 2
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)
- SAE J2012Diagnostic Trouble Code Definitions (defines P0191 as a generic OBD-II code)
P0191 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-P0191?
- 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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