DTC 44 - Diagnosing Oxygen Sensor
18-30MODEL: 90-93 MY Sedans
DATE: 4/93
Diagnostic Trouble Code 44 - Oxygen Sensor - Install Splash Shield
SUPERSEDES: TECHNICAL BULLETIN 18-17
ISSUE:
An oxygen sensor splash shield has been introduced on sedans from VIN 664941 and on all 93 MY XJS vehicles to prevent intermittent display of Diagnostic Trouble Code (DTC) 44.
ACTION:
^ Whenever replacing an oxygen sensor, make sure the splash shield is in place. On pre-VIN 664941 vehicles, install a splash shield (C 33139/4). Slide the splash shield down to cover the whole sensor, (Fig. 1).
^ If DTC 44 is displayed, check for any other stored codes. Use JDS "Engine Management - Fault Diagnosis" to read the fault table.
^ Make a note of all stored trouble code(s), then exit "Fault Diagnosis". Record preset radio stations and erase the trouble code(s) by disconnection and reconnecting the battery.
^ Run the engine to normal operating temperature. Enter JDS "Vehicle Set-Up/Individual Tests" and select "Lambda Signals".
^ If "Lambda Feedback" voltage is correct (between 1 and 4 volts) and only DTC 44 was stored, the fault is intermittent. Install an Oxygen Sensor Splash Shield (C 33139/4).
^ If "Lambda Feedback" voltage is correct and DTC 44 was combined with DTC 26, suspect intermittent fuel pressure loss. Test and inspect the fuel delivery system.
^ If "Lambda Feedback" voltage is less than 1 volt, a fault is present. Suspect faults in the following areas:
High fuel pressure.
Injectors leaking.
Purge valve stuck open.
Engine ground or oxygen sensor heater ground loose.
Incorrect air mass meter calibration.
^ If "Lambda Feedback" voltage is more than 4 volts, a fault is present. Suspect faults in the following areas:
Intake manifold air leak.
Low fuel pressure.
Purge valve stuck open.
Fuel injectors blocked or inoperative.
Air injection pump running continuously.
Oxygen sensor signal circuit fault.
Engine ground or oxygen sensor heater ground loose.
Incorrect air mass meter calibration.
Oxygen sensor bad.
For additional system and component test information, refer to the 1993 MY XJ6 Repair Manual, section 17.
^ Reset the radio station preset buttons.
PARTS INFORMATION: