P0107

P0107 means MAP signal voltage is below the floor — typically under 0.2V on a 1-bar sensor or under 0.3V on a 3-bar sensor key-on engine-off. With the engine off, MAP must read atmospheric pressure (95-101 kPa, voltage 4.5-4.8V on a 1-bar sensor, 1.4-1.6V on a 3-bar sensor) — anything under that is either a wiring fault or a dead sensor reporting vacuum that does not exist. Cheapest-first ladder: unplug the MAP connector and back-probe the 5V reference key-on, must be 4.9-5.1V (if the 5V reference is missing, check for a shorted sensor on the same 5V bus dragging the rail down — TPS, ECT, and MAP often share one 5V reference); verify ground continuity at the sensor connector, under 0.1V drop to battery negative; with the connector unplugged and key on, scan-tool MAP voltage should jump to 5V (open-circuit pulled high by ECM) — if it stays at 0V, the signal wire is shorted to ground somewhere in the harness; if voltage goes to 5V with the sensor unplugged but reads 0V with it plugged in, the sensor is internally shorted and needs replacement. P0107 with a properly powered and grounded sensor is almost always a failed sensor, but the $40 of diagnostic time to verify saves replacing a $80-$300 part that was not the actual fault.

Vehicle-specific patterns: 2008-2014 VW/Audi 2.0T TSI sees P0107 from the integrated MAP/IAT sensor failing internally with the MAP element shorting low — this is a well-documented platform-wide failure around 80k miles and the only fix is replacement; 2007-2013 GM 5.3L sees P0107 when the under-intake MAP gets soaked with coolant from a leaking intake gasket and the moisture shorts the sensor signal to ground; 2007-2018 Cummins 5.9L/6.7L Ram sees P0107 from severe soot loading of the MAP sensor in the intake horn where the soot bridges the signal pin to housing ground; 2005-2010 Chrysler/Jeep Hemi sees P0107 from a chafed MAP signal wire at the throttle body bracket grounding to the intake. Estimated repair: $40 to $400.