The vehicle has an intermittent misfire that becomes severe under load, at times to the point where it can barely be driven.

The Colorado was initially brought in for an air leak at highway speeds. During testing, it pulled a warning light (spanner symbol) and then failed to restart, logging a camshaft sensor fault. After replacement of the camshaft sensor and the intercooler, the engine ran but developed a persistent misfire. Despite cleaning the MAF, intake pressure sensor, and disconnecting the EGR, the fault persisted. Fuel rail pressure appeared mostly stable, though actual pressure dropped slightly under misfire. Boost readings were consistently lower than desired. Injector compensation values fluctuated between -3 and +3 mm³ across cylinders, with no obvious smoking during the misfire.