Engine Fuel Rail Pressure Erratic
The VOLVO-MACK-MID128-PID1569-FMI2 (Volvo/Mack D/MP Series) diesel fault code means: Engine Fuel Rail Pressure Erratic. This is a serious severity code.
Unverified. We could not confirm this code's definition against freely available manufacturer documentation, so treat the meaning, severity and fix guidance on this page as unconfirmed. Check it against the manufacturer's service information for your exact model and serial range before acting on it. This page is kept out of search engines for that reason, and we are working through this family manual by manual.
- Keep driving?
- Short distances only
- DIY difficulty
- intermediate
- Estimated cost
- $150-$600
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View pilot availability →What Are the Symptoms of VOLVO-MACK-MID128-PID1569-FMI2?
- Hard start, long cranking, or no-start
- Power loss, rough idle, surging
- Engine derate warning on dash
- Check Engine Light illuminated
- Increased fuel consumption
- Smoke (black or white) under load
What Causes VOLVO-MACK-MID128-PID1569-FMI2? (Most Likely First)
- Failed high-pressure fuel pump (aged CP-series pump) Likely
- Leaking or stuck injector returning excessive fuel Likely
- Clogged fuel filters or restricted supply line Possible
- Failed fuel rail pressure sensor Possible
- Stuck fuel pressure relief valve Less Likely
Can I Still Drive with VOLVO-MACK-MID128-PID1569-FMI2?
Short distances only. VOLVO-MACK-MID128-PID1569-FMI2 is rated serious severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What does Volvo/Mack code MID128-PID1569-FMI2 mean?
Volvo/Mack code MID128-PID1569-FMI2 (Engine Fuel Rail Pressure Erratic) is a serious-severity diagnostic trouble code set on D11/MP7, D13/MP8, and D16/MP10 diesel engines in Volvo VNL/VNR and Mack Anthem/Pinnacle/Granite/Titan trucks. It indicates a fault in the fuel rail system and should be read with Volvo Premium Tech Tool (PTT) or Mack Guided Diagnostics.
Can I drive a Volvo or Mack truck with code MID128-PID1569-FMI2?
Short distances may be acceptable to reach a repair facility, but the fault will escalate to derate (typically 55 mph then 5 mph on aftertreatment faults). Do not defer diagnosis beyond a shift.
How much does it cost to fix Volvo/Mack code MID128-PID1569-FMI2?
Typical repair falls in the range $150-$600. Sensor/wiring repairs are at the low end; EGR cooler, NOx sensor set, DEF pump, injector, or head work runs at the high end. Volvo PTT or Mack Guided Diagnostics is normally required for calibration and parameter programming.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose VOLVO-MACK-MID128-PID1569-FMI2?
Connect Volvo PTT or Mack Guided Diagnostics and observe commanded vs actual rail pressure at idle, cranking, and under load.
Replace primary and secondary fuel filters; check water separator for contamination.
Run the dealer fuel return flow / leakback test and record milliliters per injector — a high-return cylinder indicates a leaking injector.
Measure supply pressure to the high-pressure pump with a mechanical gauge (spec per service manual, typically 5-10 psi).
If supply, filters, and injectors test good, replace the high-pressure pump assembly and clean the entire fuel rail system.
After pump or injector replacement, follow the Volvo/Mack fuel system prime procedure before starting.
Which Vehicles Commonly Get VOLVO-MACK-MID128-PID1569-FMI2?
- Volvo VNL 760/860 with D13
- Volvo VNR 640 with D11/D13
- Mack Anthem with MP8
- Mack Pinnacle with MP7/MP8
- Mack Granite with MP7/MP8
- Mack Titan with MP10
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