Hi all.

I have had a 1998 V70 (non-turbo) for around 6 weeks and it is running fine. My wife phoned me at work today though to tell me the Check Engine Light was on. I got the codes pulled at a local Autozone and it showed 0172 which translates to rich mixture. The guy at Autozone said it would probably be an O2 sensor, however there appear to be 2 on the car. Since $175 a throw is quite a lot money just to see if it's that (his other option was a MAF sensor), is there a general rule as to which one fails most often? Or should I bite the bullet and replace them both anyway?

They did stock 2 parts, both Bosch, one with the full Volvo wiring loom and plug on it, the other was just 4 bare wires. The bare wires one looked to be the same part and was $99 instead of $175, is swapping the plugs over an easy option? If so, then I might just get 2 and do them both.

Once installed, do I need to get the code reset, or will it clear itself?

I should mention the car is still running just fine with the CEL on, but I guess it will fail it's smog test if I don't sort it...

Thanks for any help!

Richard

 

Before replacing anything check really good for Vaccum leaks.

 

Thanks Tech, you're a genius!

The fault was a perished rubber elbow that sits under the plastic cover to the left of the airbox (see pics). No idea what it does, but after it was replaced and I got the code cleared, the CEL stayed off.

You've saved me a fortune, thanks!

Richard


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which hose was this? the large elbow or one of the smaller ones?

 

I have a p0172 code at first it would start intermittently now it won't start at all. Help my daughter need it for College

 

98 s70 with codes 0172 and 0117 changed temperature sensor and thermostat. car has rough start and idle now won't start. do i need to change O2 sensor it so which one?

 

I don't think any car can no-start because of a bad O2 sensor. O2 sensors don't work at all when they're cold.