What would cause the amber colored engine light to come on - on a 2002 S-Type Jag?

Question

The light turned on when the car hit 30K miles.

Answer 1

The "CHECK ENGINE" light has only one function on any car sold in the United States since 1996: That is to inform the operator that the PCM (Car's Engine Control Computer)  has identified a circuit or component that is operating outside expected normal values, and this condition has the potential of causing the emissions to rise above acceptable levels. The light will not illuminate for any other reason.

Some of the causes of the light will certainly also indicate serious component failures, and some of those components may cause the engine to be seriously compromised. But other failures may have nothing to do at all with the engine (Fuel cap leak).

The proper course of action is to query the PCM with proper diagnostic equipment (either the manufacturer's data analyzer or a Scanner or code reader) and identify the diagnostic codes generated by the PCM.

These codes are circuit-specific and can identify the possible causes of the error messages. They DO NOT identify the failure.

So, if the code stored is P0171 (System too Lean; Bank 1) this is an indication that the system has identified a lean condition on bank 1. It does not necessarily indicate a failed oxygen sensor.

This code COULD be a sensor failure, but it could also be an indication of a failing fuel delivery system (pump), restricted fuel filter, failing fuel pressure regulator, a fuel injector malfunction, a vacuum leak at the engine, or even a defective power brake unit.

It is imperative to retrieve the DTCs and then proceed with Proper Diagnostics Routines to determine the actual cause of the code.