Q: My 2000 Volvo V70 XC SE is posting the codes P0422, P1171 and P1174. These codes have been coming up for as long as I've owned the car (31/2 years). The car has been to many dealerships and independent shops for diagnostics and repair. Thousands of dollars later, I still have no answers as to what is causing these codes and how to fix my car. I have replaced the electronic throttle module, transmission, steering rack, O2 sensors and thermostat several times and had the "pressure test" done to check for leaks, etc. I am just concerned that ignoring this problem is only going to lead to further problems and expenses. Any information or knowledge you can share would be greatly appreciated. The only current symptoms my car is having are a frequent antifreeze smell, yet no leak, and an inconsistent hesitation when accelerating at highway speeds. Thank you very much for your time! Sincerely, RobinA: Robin, I can help you with this problem, as I have found the same problem documented on the IATN (international automotive technicians network). First, I want you to have a head gasket leak check. If the results of that test are negative, the repair is a new catalytic converter and two new (Volvo factory brand) oxygen sensors. As long as all of your diagnostics have been performing properly, I feel very comfortable with this documented repair for this problem. Getting back to your antifreeze smell, it's possible a leaking head gasket is destroying your oxygen sensors as well as your catalytic converter. So, without repairing that problem first, there is no sense going forward with the other repairs.
Read this article in full with a
Plus Edition account.Click here to learn more 
