Hello BB Forum:

My wife's 2002 V70-2.4T wagon (230k miles) has been idling rough (and occasionally stalling at low RPM) but otherwise running fine at higher RPMs. It threw a check- engine light over the weekend. OBD diagnostics came back with codes P0134 and P0234, which apparently is the "Bank 1 Sensor1" O2 sensor and "Engine Overboost Condition". Anyone know how hard (or costly) it is to replace the sensor? I hear that they can be expensive and a pain to get loose, even with an O2 sensor wrench.

Thanks.

Bernie

I changed the both at about the same mileage on my 2004 myself. Not simple, but as I recall, routing the cable was most difficult.

For changing out an O2 sensor go to a muffler shop or garage.
It's beyond DIY, needing a lift, oxy/acetylene heat, and special tools.

But first I'd renew all of your old vacuum hoses including elbows, and also check for air leaks between the AMM and the Throttle body.

Good luck, Bill

Second what Bill said. Before replacing the O2 sensor, carefully check the condition of the vacuum hoses and the throttle body hose. Look closely for hidden cracks especially in the throttle body hose. At 20 years old if any of those are original they may need replacement.
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Will I buy another Volvo??? We'll see....