Hey there,

I finally managed to access my car's fault codes. As said, no check engine light was on.

So, after deleting most of them (only one in the aircon system, being B1967), I started my car... It ran a little lumpy at first, but then ran well. No backfiring. The engine ECU had P1260 (which seems to be regarding the immobiliser!?) and, oddly, in the AC system, P0335 was saved, which relates to issues with the crankshaft position sensor...

To my question, regarding the codes: if a code has been saved, say P0335, will the ECU check everytime if this is still working properly or will it, until the code has bee deleted, work around it (use other parameters)?

Cheers

Damien

 

After clearing the code, it ran rough relearning until it got the trims leveled out.
If you clear the code it will cycle check the system each time to see if there are any issues to allow the car to go back to normal operation vs say 'limp mode'. Take for example a bad O2 sensor....it will check it during the cycle and if its still showing a fault, even after a clear, it will register it and go to the necessary procedure to allow the engine to run until it is fixed.
For any vehicle, when you check a fault code...in your case P0355, be sure to put Jaguar in front of it because many codes are vehicle specific for how that vehicle runs and reports for an issue.

 

JTIS has a section listing all the engine OBD codes with causes and info like cycles, etc. as well as some procedures on diagnosing.

Depending on the code it may clear after a few cycles with no fault condition, many cycles, or until it is reset through a tool. The computer will be constantly checking circuits like that regardless, though how often it will check certain systems is a bit beyond me.. I believe the electrical guide CAN section also had some info on cycles and codes as well.

In the engine section there's no details on persistence about the crankcase position sensor error code, but for the security system it specifically says it will clear following an ignition on/off cycle. Although if the cause of the code is present on the next ignition it will throw the code again.

EDIT: Not entirely correct on the P1260 clearing itself. Here's JTIS quoted:
"This DTC can only be cleared following an ignition OFF/ON cycle after rectification. Attempts to clear without cycling the ignition will result in the DTC reflagging 3-4 seconds after clearing."
So, fix the cause, cycle the ignition, THEN clear, and if fixed it won't come back after a few seconds.

 

Cheers guys.

I've still got to keep an eye on this. How many cycles was it until a code is saved? I remeber reading something like 3 consistent cycles aka motor start, drive, stop.

The fault codes haven't yet reappeared, so I hope it is solved... Unless the crank sensor really is crud, but then it should technically not start at all...

 

Each code has a count. See the doc to find out. That's one of the reasons it's in the doc and available.