Exhaust Leaks

If exhaust system has large leaks, exhaust system negative pressure pulses can cause outside air to be drawn into system and past O2 sensor. Vacuum or crankcase leaks can also cause a lean condition. If Code 44 is intermittent, see INTERMITTENTS in TESTS W/O CODES article in this section.

Fig 1: Code 44, Schematic, Lean Exhaust Indication

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code 44, Flow Chart, Lean Exhaust Indication

Courtesy of GENERAL MOTORS CORP.