Engine Crankshaft Speed Signal Abnormal Frequency
The VOLVO-MACK-MID128-PID190-FMI8 (Volvo/Mack D/MP Series) diesel fault code means: Engine Crankshaft Speed Signal Abnormal Frequency. This is a critical severity code.
- Keep driving?
- No -- stop driving
- DIY difficulty
- intermediate
- Estimated cost
- $300-$1,800
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Common Symptoms
- Engine cranks but will not start
- Engine stalls at idle or under load
- Tachometer reads zero or erratic with engine running
- Intermittent engine shutdown
- Check Engine Light illuminated
Probable Causes (Ranked by Likelihood)
- Failed crankshaft position (CKP) sensor Very Likely
- Damaged or contaminated tone wheel on crank Likely
- Wiring harness fault to CKP sensor (chafing near starter or oil pan) Possible
- Excessive sensor air gap from loose mounting Possible
- ECM input circuit fault Less Likely
Step-by-Step Diagnostic Procedure
Connect Volvo PTT or Mack Guided Diagnostics and capture cranking RPM — no RPM signal during cranking confirms CKP fault.
Measure CKP sensor resistance at the ECM connector (spec per service manual; typically 800-1200 ohms for passive sensors).
Inspect sensor tip for metallic debris or oil contamination; clean and measure air gap.
Back-probe signal line and capture waveform during cranking with an oscilloscope — look for square-wave with consistent amplitude.
Inspect harness routing near starter and flywheel housing for chafe damage.
If sensor and harness test good, inspect tone wheel for missing or damaged teeth.
Frequently Asked Questions
What does Volvo/Mack code MID128-PID190-FMI8 mean?
Volvo/Mack code MID128-PID190-FMI8 (Engine Crankshaft Speed Signal Abnormal Frequency) is a critical-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 CKP 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-PID190-FMI8?
No — this fault typically triggers derate or forced engine shutdown countdown. Further operation risks engine damage or stranding. Repair before continuing service.
How much does it cost to fix Volvo/Mack code MID128-PID190-FMI8?
Typical repair falls in the range $300-$1,800. 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.