It looks like a very minor shake-up in PEI's route numbering has occurred since 2009.
GMSV imagery (1 (https://maps.google.com/?ie=UTF8&t=m&vpsrc=6&layer=c&cbll=46.557875,-64.046316&panoid=1mmrwWuMY65WdzBvx9wXYA&cbp=11,56.95,,2,5.65&ll=46.559362,-64.044049&spn=0.005341,0.01929&z=16) 2 (https://maps.google.com/?ie=UTF8&t=m&vpsrc=6&layer=c&cbll=46.561407,-64.043599&panoid=EJWAk1ErZ_7gwqS9JVOqxw&cbp=11,219.15,,1,1.59&ll=46.561413,-64.043598&spn=0.005326,0.019119&z=16) 3 (https://maps.google.com/?ie=UTF8&t=m&vpsrc=0&layer=c&cbll=46.560477,-64.004188&panoid=mEJes4yTmLNNsNOz1oH0eQ&cbp=11,10.24,,2,2.85&ll=46.560477,-64.004188&spn=0.005341,0.01929&z=16) 4 (https://maps.google.com/?ie=UTF8&ll=46.564836,-64.005146&spn=0.005341,0.01929&t=m&z=16&vpsrc=6&layer=c&cbll=46.564835,-64.005147&panoid=JNRV0W5vlSXIdZUB6lrFgQ&cbp=11,218.03,,2,5.78) 5 (https://maps.google.com/?ie=UTF8&t=m&vpsrc=0&layer=c&cbll=46.562427,-64.005082&panoid=vFHZX6RAYa3qk21T64YRtA&cbp=11,269.94,,1,4.86&ll=46.562427,-64.005082&spn=0.021363,0.077162&z=14)) from September 2009 shows a PE 183 on MacArthur Rd between PE 11 and PE 2, just a bit south of PE 11's northern end.
GeoBase GIS shapefiles, both the 2012 & 2013 revisions (and even a 2009 revision that Froggie has?) show no numbered route here.
The provincial map from Tourism PEI (http://www.tourismpei.com/pei-maps) also shows no numbered route.
GMSV imagery from August/September 2009 (1 (https://maps.google.com/?cbp=11,30.22,,1,-0.57&cbll=46.425959,-63.532559&layer=c&ie=UTF8&t=m&vpsrc=0&panoid=mUzCSPBO_712JYB_xKIAOA&ll=46.425959,-63.532559&spn=0.005339,0.019119&z=16) 2 (https://maps.google.com/?cbp=11,234.02,,1,8.26&cbll=46.431066,-63.529413&layer=c&ie=UTF8&t=m&vpsrc=0&panoid=F4aCkoVT_FF0WKro5pGq-Q&ll=46.431066,-63.529413&spn=0.005339,0.019119&z=16) 3 (https://maps.google.com/?cbp=11,136.13,,1,2.88&cbll=46.426119,-63.527746&layer=c&ie=UTF8&t=m&vpsrc=0&panoid=S8CxhxakuEH-lqDZz-nxCQ&ll=46.426119,-63.527746&spn=0.005339,0.019119&z=16) 4 (https://maps.google.com/?cbp=11,238.6,,1,3.79&cbll=46.427625,-63.52392&layer=c&ie=UTF8&ll=46.427623,-63.523915&spn=0.005339,0.019119&t=m&z=16&vpsrc=6&panoid=JTSqo1DF6YpAKLn_VsjTeA) 5 (https://maps.google.com/?cbp=11,252.8,,0,2.93&cbll=46.411767,-63.487987&layer=c&ie=UTF8&t=m&vpsrc=0&panoid=-ufwBdM7wNybQYEymMO6Bw&ll=46.411767,-63.487987&spn=0.005341,0.019119&z=16)) shows a PE 228 on Provincetown Rd, from PE 254 to PE 8 and onwards, presumably to its next junction at PE 107.
The 2012 & 2013 shapefiles have no numbered route here, instead showing a PE 228 looping off PE 2 just west of PE 239, via Hazel Grove Rd and Bertram Rd (https://maps.google.com/?q=from:+46.362889,-63.405780+to:+46.380529,-63.410152+to:+46.367601,-63.380390).
The Tourism PEI map shows PE 228 on only Hazel Grove Rd, between PE 2 and Perry Rd (https://maps.google.com/?q=from:46.378661,-63.405704+to:+46.367601,-63.380390).
The latter seems like it may be a bit more likely, as Bertram Rd doesn't look especially hi-standard, especially the northern bits, and is flagged as "This road may be seasonally closed." by Google.
Do any of you Maritimes Roadgeeks have any info from the field?