Anyone know how many miles need to be driven in order for the computer to ready for an inspection?

 

You need to run the readiness cycle- It is not a set number of miles. here is what the "book" says.

 

Thanks for the reply. Would this be the case for a 97 XJ6 though?

 

Unfortunately it doesn't relate directly to miles driven, it depends on 'drive cycles' (such as the one shown above for the V12) to complete the OnBoard diagnostic tests for:

1. Catalyst
2. O2 sensor
3. Evaporative purge system
4. Secondary air system
5. EGR system

These will eventually all complete with normal driving but it can take hundreds of miles.

I can't turn up a specific X300 6 cylinder drive cycle document but all the ones I've seen are similar to the V12 one Ross (sparkenzap) has posted.

Graham

 

Good eye! Sorry about that. Here is the MY 95 XJ6 document. JTIS many times does not repeat info for subsequent years if the info from previous years does not change, so I will bet MY 97 is pretty similiar to MY 95. And it IS somewhat different from the v-12 cycle.

BTW, you do not need to nail it exactly. If I drove 50 to 85 miles in my XJ6, at normal city speeds, it normally reset. The main point is, steady driving at varied, slower speeds. I have also heard that a 3/4 full tank helps (for the evap system test).

 

How about this method:

After a few days of normal and varied driving, they will all show ready (if all is well)... except for the catalyst monitor, which requires the steady speed driving for 3 minutes or so.

In Arizona, a 1997 model year would be allowed to pass its emissions test even if two of the monitors are "not ready," as long as there is no "check engine" light. Your state's rules may vary!

Of course you would only know this if you hooked up an OBDII scan tool. If you don't have one, the auto parts store will usually "hook one up" at no charge.