Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Engine Management
1991 Jaguar XJ-6 L6-4.0LSECTION Engine Management
A number of changes have been made in the On Board Diagnostics section of the engine management procedure to help clarify the fault table information provided on screen and trace:
The check engine warning code number (fuel fail number), as obtained from the instrument display, will also be displayed with the existing fault table information.
Many of the faults recognized by the engine management ECU can only be logged under very specific conditions, e.g. check engine number 34 will only be logged if the engine is running in excess of 2000 rpm with the vehicle decelerating and the throttle closed. This type of fault is termed a dynamic fault; it cannot be simulated under workshop conditions. Those faults that can be simulated under workshop conditions will be termed as static. Software issue DBC 4050 can recognize which type of fault is present in the ECU fault table, and will fully test all dynamic faults prior to clearing the table. Refer to the attached infomation "CHECK ENGINE FAULT FAULT DIAGNOSIS" to assist in determining the cause of fueling failure code (check engine) illumination.
The check engine warning code number (fuel fail number), as obtained from the instrument display, will also be displayed with the existing fault table information.
Many of the faults recognized by the engine management ECU can only be logged under very specific conditions, e.g. check engine number 34 will only be logged if the engine is running in excess of 2000 rpm with the vehicle decelerating and the throttle closed. This type of fault is termed a dynamic fault; it cannot be simulated under workshop conditions. Those faults that can be simulated under workshop conditions will be termed as static. Software issue DBC 4050 can recognize which type of fault is present in the ECU fault table, and will fully test all dynamic faults prior to clearing the table. Refer to the attached infomation "CHECK ENGINE FAULT FAULT DIAGNOSIS" to assist in determining the cause of fueling failure code (check engine) illumination.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.