Exhaust Leaks

If the exhaust system has large leaks, exhaust system negative pressure pulses can cause outside air to be drawn into the system and past the O2 sensor. Vacuum or crankcase leaks can also cause a lean condition.

If Code 44 is intermittent, see INTERMITTENTS in the article TESTS W/O CODES .

CODE 44 ECM TERMINAL & CIRCUIT WIRING ID (ALL W/4L80-E A/T)

Application	ECM Terminal	Wire Color
O2 Sensor Signal	C14	Purple
O2 Sensor Ground	C13	Tan

CODE 44 ECM TERMINAL & CIRCUIT WIRING ID (ALL OTHERS)

Application	ECM Terminal	Wire Color
O2 Sensor Signal	D7	Purple
O2 Sensor Ground	D6	Tan

Fig 1: Code 44 Schematic (Except 4.3L Turbo) Lean Exhaust Indication

Fig 2: Code 44 Flow Chart (Except 4.3L Turbo) Lean Exhaust Indication

If Code 44 is intermittent, see INTERMITTENTS in the article TESTS W/O CODES .

Fig 1: Code 44 Schematic (4.3L Turbo) Lean Exhaust Indication

Fig 2: Code 44 Flow Chart (4.3L Turbo) Lean Exhaust Indication