Fuel Rail Pressure Too Low
The PACCAR-P0087 (PACCAR MX) diesel fault code means: Fuel Rail Pressure Too Low. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- intermediate
- Estimated cost
- $300-$3,500
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Common Symptoms
- 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
Probable Causes (Ranked by Likelihood)
- 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
Step-by-Step Diagnostic Procedure
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.
Frequently Asked Questions
What does PACCAR MX code P0087 mean?
PACCAR MX code P0087 (Fuel Rail Pressure Too Low) 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 P0087?
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 P0087?
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.
Sources
This page is built from documented references. Verify against your own service info before repair work.
P0087 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown: