04 Xtype 3.0. check engine light came on and was for lean fuel. before I got it in the shop, it has gone off and stayed off for a week now. Any ideas about what's going on?

 

Laurie, if the problem locks in and lights the check engine light and then clears itself, the light will still remain lit for a period of time. Every time you start the car and go through a complete drive cycle (10,000 revolutions of the motor and the motor up to temp), it adds 1 to a counter inside the engine computer. When this gets up to 5, the next starting of the engine, the check engine light will go out. But, if a problem is sensed by the computer, it clears this counter (setting it back to 0) and then trips the light. So, in your case, you probably had a very short term problem, started the car a few times (more than 5) and never had the problem return.

Hopefully that makes a little bit of sense for you.

 

More importantly, the code is stored even if the light is off. get the code read and we can go from there. I find all this funny, the check engine light has been with us for 20!!!!!!!!! years now. Same story all the time. Light means a problem, and impossible to know what the problem is without finding out what code is on


I gotta add though, that is a detailed version of the truth for cars in general, and not the Jag.
The Jag drive cycle is enormously more complicated, it takes pages in the manual to write it down.

All this stuff needs to happen to get the "all systems GO" for the check engine light system.
Just reading this will show you that there is no way to know what the light came on for, without getting the code read.

this is part of it
The Comprehensive Component Monitor transmission drive cycle will “check” all transmission system components.
1 Engine and transmission at normal operating temperature. Ignition OFF
2 With gear selector in P and the ignition ON. Check gearshift interlock by attempting to move selector without pressing the brake pedal. Verify P state illumination.
3 Press and hold the brake pedal. Move the gear selector to R. Verify R state illumination.
4 Set the parking brake. Press and hold the brake pedal. Attempt to start the engine. The engine should not start.
5 Move the gear selector to N. Verify N state illumination. Start the engine.
6 With the hand brake set and the brake pedal pressed, move the gear selector to the remaining positions in the J Gate (D, 4, 3, 2) for five (5) seconds each. Verify
the state illumination in each position.
7 Move the gear selector back to 4. Verify 4 state illumination.
8 Move the gear selector to D. Verify D state illumination.
9 Move the gear selector to N. Verify N state illumination.
10 Select R, release the brakes and drive the vehicle in Reverse for a short distance.
11 Stop the vehicle.
12 Select 2 and drive the vehicle up to 65 km/h (40 mph). Hold 65 km/h (40 mph) for a minimum of five (5) seconds.
13 Select 3 and hold 65 km/h (40 mph) for a minimum of five (5) seconds.
14 Select 4 and hold 65 km/h (40 mph) for a minimum of five (5) seconds.
15 Select D and accelerate to a minimum speed of 80 km/h (50 mph). Hold 80 – 129 km/h (50 – 80 mph) for a minimum of 1.7 kilometers (1 mile).
16 Stop the vehicle; do not switch OFF the engine.
17 Use WDS Datalogger “TOTAL NUMBER OF DTC SET” to ensure that transmission DTC monitoring is complete.

here is more...
Ensure that fuel filler cap is fully closed (minimum three clicks).
2 Fuel level > 30% and < 85%.
3 Using WDS, perform ECM DTC Clear (even if no DTCs are flagged).
4 Drive vehicle for a minimum of 2 minutes, and until engine is at normal operating temperature.
5 Using WDS, ensure that the EVAP Canister Purge Valve is operating by observing “PURGE VAPOR MANAGEMENT VALVE – DUTY CYCLE”. If the valve is not
active, ECM adaptions have not been learned. Conduct a “green ECM” Drive Cycle as described in Technical Service Bulletin.
6 Drive vehicle to the road where the EVAP System Drive Cycle will be conducted. Stop vehicle and switch OFF the ignition. Leave ignition OFF for 30 seconds,
then restart the engine.
7 Accelerate briskly to 80 km/h (50 mph) ensuring that the engine speed reaches a minimum of 3500 rpm for a minimum of 5 seconds.
8 (0.040 inch EVAP Test) View WDS “PURGE VAPOR MANAGEMENT VALVE – DUTY CYCLE”, “CANISTER CLOSE VALVE – VAPOR RECOVERY SYSTEM”, and
FUEL TANK PRESSURE – VAPOR RECOVERY SYSTEM”. Avoiding high engine loads, drive the vehicle steadily between 65 km/h (40 mph) and 100 km/h (60
mph). Avoid driving conditions that will produce excessive fuel movement. WDS should give an indication that the test is active (it may take up to 30 minutes
before the test will initialize). When the test has initialized (EVAP Canister Close Valve CLOSED), it will take approximately 90 seconds for the test to complete.
9 (0.020 inch EVAP Test) Continue driving vehicle as explained in Step 8 for an additional 10 minutes.
10 Gently coast the vehicle to a stop. Allow the engine to idle for 2 minutes and view WDS “PURGE VAPOR MANAGEMENT VALVE – DUTY CYCLE”, “CANISTER
CLOSE VALVE – VAPOR RECOVERY SYSTEM”, and FUEL TANK PRESSURE – VAPOR RECOVERY SYSTEM”. WDS should give an indication that the test is
active. When the test has initialized (EVAP Canister Close Valve CLOSED), it will take approximately 90 seconds for the test to complete.
11 If the 0.020 inch EVAP Test is not activated, the purge system vapor concentration may be too great. To reduce the vapor concentration proceed as follows:
12 Drive the vehicle for an additional 30 minutes avoiding driving conditions that will produce excessive fuel movement. Repeat Step 10. If the 0.020 inch EVAP
Test is still not activated, repeat the Drive Cycle from Step 6.


Even more ---
HEATED OXYGEN SENSORS MONITOR DRIVE CYCLE
Upstream (Universal) oxygen sensors:
1 Engine OFF; cooling fans inoperative > 20 seconds.
2 Start engine and bring to normal operating temperature > 82 °C (180 °F).
3 Drive the vehicle between 3000 – 4000 rpm at a steady speed. Lift foot completely off accelerator and coast to a stop within 30 seconds. Do not touch accelerator
pedal for 4 seconds after coming to a stop.
4 Repeat step 3.
5 Idle engine for 11 minutes.
Downstream oxygen sensors:
1 Start engine and bring to normal operating temperature > 82 °C (180 °F).
2 Drive the vehicle steadily between 48 – 97 km/h (30 – 60 mph) for 10 minutes.
3 Drive the vehicle above 3000 rpm in 4th gear at a steady speed. Lift foot completely off accelerator and coast for 30 seconds.
Oxygen sensor heaters:
1 Start engine and bring to normal operating temperature > 82 °C (180 °F).
2 Idle engine for 3 minutes.
ADAPTIVE FUEL MONITOR DRIVE CYCLE
1 Start engine and bring to normal operating temperature > 82 °C (180 °F).
2 Idle for a minimum of 10 minutes.

 

holy moly! I did get a reading of the fuel system running lean. After the auto parts store read the code, I made a service appt and then the light went off!

 

you should probably check the IMT o-rings and the PCV hose. Leaks there will kick of the bank 1 or bank 2 lean code. There have been a bunch of us that have had similar issues lately. It will probably come back more and more frequently...

 

The easy way to check the IMT o-rings is to listen for a hissing or sucking sound when the engine is running. They're located on the pass side of the engine, and are 2 black "caps" on the intake. Just start it up, pop the hood and listen to those 2 caps. If you hear hissing/sucking, it's worth the $15 to get new rings and pop them in. It's a real easy fix.

 

UPDATE: My brother had to replace the battery and the codes cleared for awhile. Well, this past week the car had trouble starting again and CEL came back on. Same codes. Do we just need to replace the sensors?P1366 TDC Sensor No. 2 Intermittent InterruptionP0366 P0369 Camshaft Position CMP Sensor B Intermittent