O2 Sensor Replacement

Donny1973 · Post by **Donny1973** » 02 Jun 2009, 16:05

My 2001 C70 convertible 2.4 is throwing a P0422 and the CEL is on. It's running great with no real issues, but I went ahead and bit the bullet and bought both O2 sensors. I heeded the advice of the board and went with Bosch direct OE replacement sensors. I'll be tackling the job this weekend.

I haven't had the car very long and haven't had a chance to look at the sensors to see what it's going to entail. Also, can't find a shop/repair manual that covers the '99 and up C70. Can someone (who has personally changed both sensors on a similar car) give me a breakdown of the steps involved? Can they both be accessed form underneath? What has to be removed? Should the car be lifted from the side, front or rear? Should I buy the O2 sensor socket, etc? I've done a search and have found conflicting info on what to expect.

Thanks,
Donny

Post by **vegasjetskier** » 02 Jun 2009, 17:52

C70OxygenSensorReplacement2001.pdf: (52.66 KiB) Downloaded 315 times

Donny1973 · Post by **Donny1973** » 15 Jun 2009, 08:34

I changed both O2 sensors in one hour including the 15 minutes it took to figure out how to undo the connector for the rear sensor. The job was a piece of cake. Didn't have to drop the DP or use any penetrating oil. I decided to pull out the MAF pipe to get better access to the connectors from above. While at it, I cleaned the MAF sensor, changed the majority of the vacuum lines and replaced most of the plastic wire loom which was brittle and crumbling. I cleared the P0422 and took it for a short test drive. Within 20 miles the CEL was back on, P0422 again. Very disheartening.

Anyone have a suggestion as to what I should do next? I don't want to keep throwing money at the car. So far I've changed the spark plugs, replaced three coils, both O2 sensors and most of the vacuum lines. The gas cap and rubber seal look okay.

This is my first Volvo and I really like it, but my fondness is quickly fading. It runs great, however if I can't resolve this problem it will irritate me to the point that I will wind up selling it and going back to BMW, which I really don't want to do. Any advice from the experts would be greatly appreciated.

Donny

dusty · Post by **dusty** » 17 Aug 2009, 20:18

Hi, have you checked for vacuum leaks? If the engine idle surges while carefully spraying some carburetor cleaner or starting fluid around the vacuum hoses, you have a leak there. It should go without saying but be extremely careful spraying anything flammable like this around a hot engine. Also check the intake & exhaust manifold bolts for the correct torque. If they are too loose, I would recheck the torques after a few days of driving. Could also be a leak in the exhaust anywhere in front of the catalytic converter I believe.