P1106

P1106 is GM's Manifold Absolute Pressure Sensor Circuit Intermittent High — the MAP signal voltage briefly spiked above the expected operating window during a drive cycle, then returned to normal, and the ECM logged the glitch. On a typical GM 5V-reference MAP sensor, you should see 1.0-1.5V at key-on engine-off (atmospheric pressure), 1.0-1.8V at warm idle (high vacuum pulling the sensor LOW), and 2.5-4.5V under WOT or boost (low manifold vacuum or positive pressure pushing the sensor HIGH). An intermittent-high fault means the signal jumped to ~4.7V+ briefly when it shouldn't have — usually wiring, rarely the sensor itself. Cheapest-first ladder: (1) Unplug the MAP connector, inspect for green corrosion or pushed-back pins, dielectric-grease and reseat ($0). (2) Wiggle-test the harness with the engine idling and the scan tool live-graphing MAP voltage — if the spike correlates with a wiggle, you've found a broken wire or chafe-through to a heat source. (3) Verify the 5V reference is steady (should be 4.9-5.1V) and the signal ground is clean (<0.1V drop to battery negative). (4) Pull the sensor, blow out the vacuum port with compressed air (carbon can plug it on high-mileage trucks), and re-test. (5) Replace the MAP sensor itself ($45-$90 OEM) only after the wiring checks out. Don't condemn the MAP before checking the vacuum source — a cracked vacuum hose to the sensor will mimic an intermittent-high signal because the sensor sees atmospheric pressure instead of manifold vacuum.

Vehicle-specific patterns: 1999-2013 Silverado / Tahoe / Suburban / Sierra / Yukon / Escalade with the LS-based 4.8/5.3/6.0/6.2 (LM7, LR4, LQ4, L59, LMG, L92, L9H) — the MAP sensor sits at the rear of the intake manifold under the throttle body and gets baked by heat soak from the firewall; the connector pins corrode and the sensor's vacuum port carbon-clogs from PCV oil mist. 2005-2010 Cobalt / Cruze / Equinox with the Ecotec 2.0/2.2/2.4 (LSJ, LE5, LAF) throws P1106 from a cracked intake-manifold-mounted MAP vacuum reference passage on early models. 2010+ Camaro / CTS / Traverse with the LFX/LLT 3.6L V6 throws P1106 when carbon buildup around the MAP sensor port distorts the vacuum signal. 2006-2010 Silverado/Sierra HD with the LBZ/LMM Duramax has a boost-pressure sensor (functionally the MAP equivalent) that fails intermittently from soot fouling at the air-horn mount — clean it with throttle-body cleaner before condemning. Estimated repair: $0 (reseating a connector or vacuum hose) to $180 (OEM MAP sensor + pigtail repair).