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.

CODE 44 ECM TERMINAL & CIRCUIT WIRING IDENTIFICATION

Application

ECM Terminal

Wire Color

All With 4L80-E Transmission ⁽¹⁾

Oxygen Sensor Signal

C14

Purple

Oxygen Sensor Ground

C13

Tan

2.5L, 2.8L & 3.1L & "C", "K" & "P" Series 4.3L ⁽¹⁾ & V8 (All With M/T)

Oxygen Sensor Signal

Purple

Oxygen Sensor Ground

Tan

⁽¹⁾	The 4.3L oxygen sensor has 3 wires: sensor signal, common ground and heating element.

Fig 1: CODE 44, Schematic, Lean Exhaust Indication

Fig 2: CODE 44, Flowchart, Lean Exhaust Indication