Advice for CEL coded P1128 & P1130

[eiblanco]

I had a 1128 and 1130 error code and followed the advice of several posts and found that the oil filler cap was difficult to remove when running. I also heard an air leak after removing the rear engine cover. There were also a couple of instances of a lot of smoke coming from the exhaust at start-up only. So I changed the oil air separator and the CEL has stayed off since. The idle has improved and so has the gas milage.

[Tony14]

Was getting 1128 AND 1130 codes from the CEL condition on my '99 2.5L Boxster. Took it to a pro and got the oil filler tube replaced. Within 75mi the CEL was back on throwing the same 1128 AND 1130 codes (both cyl. banks reaching rich threshold, in otherwords, running lean). I decided to try to figure this out myself. Consulted this and other forums. Replaced fuel cap. Still got 1128, 1130. Bought some MAF cleaner and spent about 45 min accessing the engine compartment, removing and cleaning the MAF (installed new air filter while I was in there, old one was clean but replaced it anyway) and putting it all bact together. Reset the codes with my Actron 9950 OBD II gadget and went for a spin. Codes have not returned thus far and I must say, my Boxster is running like it was new! A VERY noticable improvement in performance. Thanks for all the advice! The Forums are a great source for information. If codes return, I'll let you know.
1999 Boxster
51,800 mi.
Artic silver, Sport Package
Totally stock