clearly a sensor is reporting a fault to the ecu. there is a way of getting the code from shorting out two leads in the passenger side engine compartment it is lsited I believe on mkiv.com which is down for repairs right now
alternatly go to a dealer and get them toread teh code for you on your year it has obd1 and the info provided is less but will point you in the right direction might be soemthing simple like a bad O2 sensor..