thanks for the tip...the gas cap was the 1st thing I checked ..it was not tight,,,but it didnt make a difference..the light came back on

 

may not help you, but when I first bought my XKR I would get “Check Gas Cap” messages all the time. It seems perfectly tight, and the gasket appeared to be in good condition.

But I thought, what the heck, a new Jaguar branded cap was inexpensive, and worth a try.

Once the new cap was installed, the gas cap fault messages went away. It’s been 5 years since then and no problems with the cap.

Z

 

good to know...I haven't had any "check gas cap" warning yet...just the engine light on

 

P0442 EMS
OBD II
EVAP system leak detected –
small (0.040 in.)
Evaporative system monitor drive cycle – page 7
2 N ECM Default:
– Canister purge inhibited
– Adaptive fuel metering inhibited
— Fuel cap not fitted correctly
Fuel cap seal defective
EVAP system leak (canister damage, pipework damage)
EVAP Canister leaking
EVAP canister close valve failure
Fuel tank leak

This is a minor fault that takes 2 drive cycles before the Check Engine Light appears. If the ECM cleared the code itself, it is likely a very small leak. I always clear codes 3 times in a row to eliminate the 'pending" and "historic" stored codes. That may not solve the problem but might give you a few trips without the annoying light on. That, along with cleaning the cap & filler, and keeping the battery fully charged, may be enough to avoid future CELs.

See "page 7" below from Powertrain DTC Summaries – OBD II
Quick Reference Diagnostic Guide. The tests can't be thoroughly performed without a WDS laptop but it gives oversight into the EVAP test process.

EVAPORATIVE SYSTEM MONITOR DRIVE CYCLE
1 Ensure that fuel filler cap is correctly fitted and fully closed (minimum three clicks, clockwise).
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.
13 Using WDS, check for and clear flagged DTCs.

 

WOW! this is indeed very comprehensive testing instructions!
I must admit -tho I have -as a backyard mechanic- over my 53 years working on cars and motorcycles
and doing every sort of repair including rebuilding of motors
and having enough computer knowledge to be a webmaster of my commercial website
this diagnostics may be just a bit beyond my abilities
That said I will TRY these suggestions as best I can
A BIG THANKS again for all the help and support to jrnsr and all members !