300's are miss fire cylinder numbers....300 being Random Missfire....170 and 173 are fuel/adaption codes...when there's an adaption erase..ie: when someone erases all adaption stratagies...the miss fire's come along next as a rule.

Are you sure he did not do anything else other than collect the codes ?
The engine often gets miss fires from faulty plug resistors and plugs coils too.


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