I recently purchased a code reader which produces a whole load of codes, one even says the anti theft imobiliser has been deployed when it obviously hasn't, the car seems to work fine with the exception of a sporadic ABS code which I am trying to solve so am I to assume these codes are largely historic?
I would like to clear these codes to make it easier to identify any current/new ones, question is can clearing all these codes have any detrimental effect on the car's sensitive inner feelings?, I am of the "if it aint broke don't fix it" school of thought and wouldn't want to upset the apple cart.

 

My approach has always been to clear the codes and start from scratch....

Which OBDII scanner did you purchase?

 

Yes, I am inclined to do that but have hovered over the button a couple of times with a little voice from over my shoulder saying "leave it, you'll regret doing that".

I got the iCarsoft LR 2.0 but it is throwing all sorts.

 

I have a frosty relationship with my iCarsoft i930 scanner as well (I have owned it for nearly five years). Sometimes it will read certain modules and sometimes it will not. I have downloaded software updates from the iCarsoft website several times (but not recently). And iCarsoft's complete absence of customer support is a major drawback. While this scanner has indeed helped me with certain issues, it has been worthless with other issues that it is supposedly capable of diagnosing. My advice for any iCarsoft product is always buyer-beware and make certain your purchase comes with a decent return policy....

 

Clearing the codes will not have any negative effect on the car whatsoever.

 

Whenever diagnosing a fault I like the READ, PRINT and CLEAR so I can start fresh.
I also like to read and clear the EDR (Engine Data Recorder) P1582 if equipped and then clear if not relevant.

Test drive car or return to customer for monitoring (if the DTC is inconsistent or irregular).
If/when fault returns, you have more accurate data.

If you want to clear the engine adaptations, you need to disconnect power from the ECM. (Remove ECM fuse or disconnect battery)
Clearing codes will not reset things like FUEL TRIMS etc.

 

JLR advice to Dealers is NOT to automatically clear down codes although it wasn't always like this. The reasoning behind it is Jaguar SDD (Symptom Driven Diagnostics) depends on the stored code sequence which are all recorded by distance. Here's an example from my XK:




That being said, in some circumstances, clearing down is unavoidable and, if you're not using SDD, it doesn't matter anyway.

As motorcarman advises, READ, PRINT and CLEAR in that order. A code is going to reset if the fault has not been resolved.

Graham