Engine Camshaft Speed Signal Erratic
The VOLVO-MACK-MID128-PID723-FMI2 (Volvo/Mack D/MP Series) diesel fault code means: Engine Camshaft Speed Signal 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-PID723-FMI2?
- Rough running or extended crank time
- Engine may run on CKP backup only (reduced power)
- Check Engine Light illuminated
- Possible misfire code on specific cylinders
- Engine derate
What Causes VOLVO-MACK-MID128-PID723-FMI2? (Most Likely First)
- Failed camshaft position sensor Very Likely
- Damaged camshaft tone wheel or worn key Possible
- Wiring harness damage near valve cover Likely
- Loose sensor mounting causing excessive air gap Possible
- ECM input circuit fault Less Likely
Can I Still Drive with VOLVO-MACK-MID128-PID723-FMI2?
Short distances only. VOLVO-MACK-MID128-PID723-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-PID723-FMI2 mean?
Volvo/Mack code MID128-PID723-FMI2 (Engine Camshaft Speed Signal 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 CMP 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-PID723-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-PID723-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-PID723-FMI2?
Connect Volvo PTT or Mack Guided Diagnostics and monitor CMP signal live; compare to CKP for cam/crank correlation.
Measure CMP sensor resistance and supply voltage at the sensor connector.
Inspect sensor mounting bolts for correct torque and check tip for debris.
Back-probe and capture CMP signal waveform with oscilloscope during cranking.
Inspect harness routing on valve cover for heat damage or chafe.
If sensor and harness test good, verify timing gear and key are intact on the camshaft.
Which Vehicles Commonly Get VOLVO-MACK-MID128-PID723-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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