Diagnostic Aids

Using scan tester, observe block learn values at different RPMs. Scan tester also displays block cells, so block learn values can be checked in each of the cells to determine when Code 44 set. If conditions for Code 44 exist, block learn values will be approximately 150.

• Ensure O2 sensor pigtail is not contacting exhaust manifold.
• Check for ground in wire between connector and O2 sensor.
• Water delivered to fuel injectors can cause a lean mixture. This can set a Code 44.
• Fuel system will be lean if pressure is too low. Monitor fuel pressure while driving at various road speeds and/or loads to confirm a problem (if necessary).
• If exhaust leak is present, outside air can be pulled into the exhaust and past the sensor. Vacuum or crankcase leaks can also cause a lean condition.

For intermittent inspection, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - FUEL INJECTION article.

Fig 1: Code 44 - Schematic (SOHC)

Courtesy of ISUZU MOTOR CO.

Fig 2: Code 44 - Diagnostic Flowchart (SOHC)

Courtesy of ISUZU MOTOR CO.