Detailed guide for MID 128 PID 102 FMI 0
Back to top ↑MID 128 PID 102 FMI 0 - Intake Manifold Pressure Too High
**Technical Background**: This fault triggers when boost pressure exceeds 400 kPa (4.0 bar / about 58 PSI) [citation:2]. On Volvo D13 engines, the ECM monitors boost pressure via the Intake Manifold Pressure Sensor (combined pressure/temperature sensor in intake manifold).
⚠️ Why This Matters
Overboost can cause:
- Engine mechanical damage (higher cylinder pressures)
- Turbocharger overspeed (catastrophic failure)
- Exhaust gas temperature spikes
🔧 Common Root Causes
**1. VGT Actuator Stuck Closed**
The Variable Geometry Turbocharger (VGT) uses vanes to control boost. If vanes stick in the "closed" position (smallest flow area), boost builds too quickly [citation:4]. This is often caused by carbon/soot buildup from incomplete regeneration or excessive idling.
**2. VGT Control Valve Failure**
On air-controlled VGT systems, a failed control valve can send full air pressure to the actuator, forcing vanes closed.
**3. Faulty Boost Sensor Reading**
If the sensor reads low, the ECM commands more turbo, but actual boost may be normal—creating a control loop error.
🛠️ Diagnostic Steps
**Visual Inspection:**
- Check VGT actuator rod movement with engine off (should move freely)
- Look for carbon buildup on turbo nozzle (if accessible)
- Inspect vacuum/air lines to actuator for leaks
**With Diagnostic Tool (PTT/INSITE):**
- Monitor desired vs actual boost pressure
- Check commanded VGT position
- Run VGT actuator calibration (requires special procedure)
**The "Boost Leak" Paradox:**
Sometimes a leak AFTER the turbo (intercooler boots) causes the turbo to work harder to maintain boost, but the sensor reads atmospheric—not this fault. FMI 0 specifically means sensor reads TOO HIGH.
📸 Free Images
- "VGT turbocharger cutaway" (educational fair use)
- "Carbon buildup turbo vanes" (search on Wikimedia Commons)
💬 Field Experience
*"On CM870 engines with delete programming, FMI 0 can happen from bad tuning. The ECM commands full boost but the delete tune messes with the expected values."* — Rawze.com forum [citation:9]
*"After 500k miles, pull the EGR cooler and clean the turbo vanes. It's preventative maintenance on these engines."* — Volvo specialist
Mechanic community notes for MID 128 PID 102 FMI 0
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