We have a 52 reg Zafira 2.0 dti . We suffered with this problem for 2 years.  It was difficult to diagnose; twice the Vauxhall agents charged us £87.60 but could not find "stored codes". 
The problem light only appeared after 10 miles on the motorway- and always had the same pattern - flashed on 3 times 5 minutes apart then stayed on- with consequent loss of power.  
back to our trusty local garage - one diagnostic machine could not find the fault - but a second one did.  Faulty EGR valve - so we got one supplied at a price of £120
However that left the problem exactly the same.  Back to the garage - same diagnotic - it turns out that the Vauxhall spares supplier had not supplied an EGR valve but something else- after getting the real EGR valve - (cost £250) problem solved!
                
 P O'B
                
 March 2008