Diagnostic Aids
- Indications of HO2S failure may be a strong smell of rotten eggs until default condition is initiated, high CO readings and/or MIL is illuminated. Check for contaminated sensor, poor connections, loose terminals, and open or shorted wires. Ensure wiring to primary sensors is not crossed. See WIRING DIAGRAMS
. See Figure
, Figure
and Fig 1
.
- With engine running at normal operating temperature, measure HO2S output voltage between HO2S 4-pin connector terminals No. 1 and 2. See Fig 1
. Output voltage on primary HO2S should change between approximately 0.2 volts (rich mixture) and approximately 4.7 volts (lean mixture). Using a Snap-On PAC, compare wave pattern with known-good wave patterns. See Fig 2
. Oxygen content of exhaust gases after catalytic converter should be nearly constant, causing little voltage change in secondary HO2S.
- Measure HO2S heater resistance between sensor connector terminals No. 3 and 4. See WIRING DIAGRAMS
. See Fig 1
. HO2S heater resistance at 68°F (20°C) should be approximately 5.7 ohms. When HO2S related DTC repairs are completed, perform DRIVE CYCLE: "C"
.
Courtesy of LAND ROVER NORTH AMERICA, INC.
Courtesy of LAND ROVER NORTH AMERICA, INC.