You know, I am not 100% sure if you need to replace the computer. Read this thread and it can point you in the right direction.
You can also post on this forum and they will help you with the best course of action concerning your Opel.
Codes are as follows
-p1155 I don't think this code pertains to your car. It doesn't pop up anywhere but for Mazdas.
- p1122 throttle position sensor
- p1120 also appears to deal with the TPS circuit
Tuesday, March 19th, 2013 AT 12:35 AM