Note On Intermittents

PCM Code P034 is usually set by a vacuum supply problem to MAP sensor. Check for improper vacuum routing, MAP hose not connected to proper throttle body port or MAP hose chafed, pinched or cut. Apply vacuum to MAP hose at throttle body, and look for vacuum leaks in MAP hose or MAP sensor.

Fig 1: PCM Code P034 Schematic - MAP Sensor Signal Too High

Courtesy of GENERAL MOTORS CORP.

Fig 2: PCM Code P034 Flow Chart - MAP Sensor Signal Too High

Courtesy of GENERAL MOTORS CORP.