Transmission Output Shaft Speed Erratic
The VOLVO-MACK-MID216-PID191-FMI2 (Volvo/Mack D/MP Series) diesel fault code means: Transmission Output Shaft Speed Erratic. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- advanced
- Estimated cost
- $400-$3,500
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Common Symptoms
- Transmission warning lamp illuminated
- Harsh or missed shifts (I-Shift/mDRIVE)
- Neutral lockout or limp-home mode
- Engine will not start (neutral safety fault)
- Check Engine Light with trans fault code
Probable Causes (Ranked by Likelihood)
- Failed output shaft speed sensor Likely
- Wiring harness damage at transmission connector Likely
- Low transmission oil level or wrong fluid type Possible
- Clutch wear (for clutch actuator codes) out of adjustment range Possible
- TCM internal fault Less Likely
Step-by-Step Diagnostic Procedure
Connect Volvo PTT or Mack Guided Diagnostics (transmission module) and verify MID216-PID191-FMI2 active; read live shaft speeds, clutch position, temp.
Inspect transmission harness for chafe or damage at the case connector and mid-frame crossover.
Check transmission oil level at operating temperature; top up with correct Volvo/Mack spec fluid.
Run clutch calibration / shift actuator learning via PTT or Guided Diagnostics.
Measure sensor resistance at the sensor or TCM connector per service manual spec.
If fault persists after wiring and sensor checks, TCM replacement with programming may be required.
Frequently Asked Questions
What does Volvo/Mack code MID216-PID191-FMI2 mean?
Volvo/Mack code MID216-PID191-FMI2 (Transmission Output Shaft Speed 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 output shaft speed 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 MID216-PID191-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 MID216-PID191-FMI2?
Typical repair falls in the range $400-$3,500. 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.
Sources
This page is built from documented references. Verify against your own service info before repair work.