P0106: How to Diagnose & Fix — MAP/Barometric Pressure Circuit Range/Performance

The 1.4L turbocharged Ecotec engine in the Sonic shares the notorious PCV system failure with the Chevrolet Cruze. The PCV regulator diaphragm integrated into the valve cover ruptures, causing massive vacuum leaks. Additionally, the intake manifold check valve (small red/orange valve) fails, compounding the issue. GM extended coverage for the cracked PCV diaphragm to 10 years/120,000 miles on certain 2012-2014 Sonics (special coverage N202299080) and 2015 Sonics (N192210230).

Vans built with the 6.0L L96/LC8 Vortec V8 (the volume engine in Express 2500/3500 from 2010 on) can break a rocker arm, producing an engine tick and a hard misfire on one cylinder. GM addressed it in preliminary information bulletin PIP5522B, which specifically lists 2017-2018 Chevrolet Express among the affected vehicles and warns that a broken rocker arm can let the valve drop into the cylinder and cause catastrophic engine failure. The Express 4.8L L20 and 6.0L L96 do not use Active Fuel Management, so the AFM collapsing-lifter story that plagues Silverado/Tahoe 5.3L and 6.2L engines does not apply to these vans - this is a rocker/valvetrain hardware failure, not an AFM lifter failure. Owners typically hear a distinct top-end tick that does not go away as the engine warms, followed by a stored misfire code.

The engine wiring harness splices that feed the Manifold Absolute Pressure (MAP) sensor were crimped with insufficient compression on 2013-2014 Escapes with the 2.0L engine built October 5, 2011 through April 1, 2013. The loose splice sends an incorrect MAP signal to the powertrain control module, and the PCM responds with hesitation, a rough or unstable idle, or an outright stall — often with no stored code that points at the harness, because the sensor itself tests good. Ford recalled the vehicles (along with 2.0L Focus ST) under 14S17 (NHTSA 14V495000), then issued 14S17-S1 (NHTSA 15V813000) for 2013 Escapes built January 11, 2012 through April 1, 2013 and 2013-2014 Focus ST that had been repaired before 14S17 with an earlier procedure that may not have fixed the splices properly. This is an electrical-connection defect and is completely separate from the 1.6L coolant intrusion and cylinder-head cracking issues that dominate this generation, though it affects many of the same cars.

The 1.4T engine in the first-generation Cruze has the PCV system integrated into the valve cover assembly. The PCV diaphragm ruptures, the check valve fails, or the valve cover gasket deteriorates, causing oil leaks, vacuum leaks, rough idle, and check engine lights. The failed PCV system creates excess crankcase pressure that pushes oil past seals and into the intake manifold. This is the same fundamental design flaw as the Equinox and Malibu 1.5T PCV system. GM released an updated valve cover with improved PCV components.

A defective supplier batch of valve springs went into GM V8 engines built between June 1 and September 15, 2020, including the 6.2L LT2 in the C8 Stingray. Springs broke at astonishingly low mileage — documented C8 failures at 57 miles and at 115 miles, one of which required a flatbed tow. A broken spring drops valve control on that cylinder, producing a misfire, an audible tapping or clattering engine noise, a check engine light, and in the worst case valve-to-piston contact that destroys the head or the engine. GM acknowledged the defect in service bulletin PIP5752A on September 22, 2020, covering seven V8 families (L87, LT1, LT2, LT4, L82, L84, L8T). Owners subsequently reported failures on engines built past the September 15 cutoff, and GM extended the affected build window, so the published date range should be treated as a floor rather than a boundary. This is a discrete supplier defect and is unrelated to the LT2's lifter-tick and DFM behavior.