Last year, my van stared giving me a P0301 code. The symptoms were rough idle when the car is started but smooths out after a minute. After multiple trips to the dealer cause was never determined. Researching I found that later model Caravans had faulty PCMs that required reflashing for erroneous misfire codes, but the dealer told me that for 03’s this did not apply.

Recently the van started dumping a P0133 and P0171 code along with my old friend PO301. Up until today no new symptoms presented themselves. This afternoon my wife told me the van started to buck and miss intermittently.
I purchased an upstream o2 sensor from the dealer and planned on replacing it this evening. Easier said than done. After drenching it with PB40 it wouldn’t budge. I’m going to add some more tonight and try again in the morning.

I then connected the vehicle to my laptop to look at some realtime data. Before this I cleared all the codes to see if they would come back. When I tried to clear them with my handheld unit, they did not clear. To my surprise the codes did clear, and they haven't come back. The van so far is driving fine.

My question is this, can clearing stored codes cause drivability issues to disappear?

Thanks.

P.S. Sorry for the long lead up.

 

I decided to replace the #1 Plug. Sure enough it was fouled up. Van runs much better now.

 

(error - delete my post)