Diagnostic Aids
Ensure O2 sensor pigtail is not contacting exhaust manifold. Check for ground in wire between connector and sensor. If an exhaust leak is present, outside air can be pulled into the exhaust system, causing a lean condition at the sensor. If M/C solenoid does not "click" with ignition on and test terminal grounded and there is no Code 23, check for sticking solenoid. Inlet air temperature switch may be open. Inlet air temperature switch should be closed at less than 32°F (0°C). If code is intermittent, see TESTS W/O CODES article.