Engine Oil Pressure Sensor Voltage Below Normal
The VOLVO-MACK-MID128-PID100-FMI4 (Volvo/Mack D/MP Series) diesel fault code means: Engine Oil Pressure Sensor Voltage Below Normal. This is a moderate 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?
- Yes, but fix soon
- DIY difficulty
- intermediate
- Estimated cost
- $150-$600
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View pilot availability →What Are the Symptoms of VOLVO-MACK-MID128-PID100-FMI4?
- Check Engine Light illuminated
- Affected gauge reads zero or maximum
- Possible engine derate
- Fault code active on scan tool
- May affect cold start performance
What Causes VOLVO-MACK-MID128-PID100-FMI4? (Most Likely First)
- Failed oil pressure sensor element Very Likely
- Open, shorted, or chafed wiring to sensor Likely
- Corroded or backed-out connector pin Likely
- 5V reference supply out of spec Possible
- ECM input circuit fault Less Likely
Can I Still Drive with VOLVO-MACK-MID128-PID100-FMI4?
Yes, but fix soon. VOLVO-MACK-MID128-PID100-FMI4 is rated moderate severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring it.
Frequently Asked Questions
What does Volvo/Mack code MID128-PID100-FMI4 mean?
Volvo/Mack code MID128-PID100-FMI4 (Engine Oil Pressure Sensor Voltage Below Normal) is a moderate-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 oil pressure sensor 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-PID100-FMI4?
Limited short-term operation is usually possible, but the fault will illuminate the Check Engine Light and should be diagnosed promptly to avoid cascading aftertreatment or fueling faults.
How much does it cost to fix Volvo/Mack code MID128-PID100-FMI4?
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-PID100-FMI4?
Connect Volvo PTT or Mack Guided Diagnostics and monitor live data for oil pressure sensor — compare against known-good spec.
Unplug sensor connector and inspect for bent, corroded, or backed-out pins; check for moisture intrusion.
Measure 5V reference at signal return line (should be 4.9-5.1V key-on with sensor unplugged).
Measure sensor resistance across signal and return pins per Volvo/Mack service information.
Back-probe harness and wiggle-test while watching live data for intermittent faults.
If sensor tests in-spec, inspect harness between sensor and VECU for chafing.
Which Vehicles Commonly Get VOLVO-MACK-MID128-PID100-FMI4?
- 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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