EGR Valve Position Control Circuit Shorted

Volvo/Mack code MID128-PID2791-FMI6 (EGR Valve Position Control Circuit Shorted) 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 EGR valve system and should be read with Volvo Premium Tech Tool (PTT) or Mack Guided Diagnostics.

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.

Typical repair falls in the range $600-$3,200. 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.

California's heavy-duty OBD regulation sets the low-flow trip point where a decrease from the manufacturer's specified EGR rate would push NMHC, CO or NOx past 2.0 times the applicable standards, or PM past the standard plus 0.02 g/bhp-hr (Title 13 CCR 1971.1, section (e)(3.2.1)). Note the second route: it must also flag the case where the EGR system has hit its control limits and simply cannot reach the commanded flow — so this code can set with the valve working and the system still unable to deliver. This threshold comes from the heavy-duty OBD regulation, which covers 2010 and later heavy-duty engines. If your engine is in a pickup at or under 14,000 lb GVWR it is certified under the separate medium-duty rule instead, so treat this as the design intent rather than your engine's exact limit.