While sitting in traffic this morning I got an error 2187 (system too lean at idle). It was a wet morning but I tend to drive carefull due to to the CPE CAI(it has a rain coat on the filter). As well I had just filled her up using VPower & had travelled 50km on the new tank. I did not notice any diffence with idling or anything else. I cleared the error code using the scan gauge. Any ideas what could of caused the error ?