ETS light is on and P0121 Code

[mmeasterb]

No throttle response when running. The next morning it won't start. Sounds flooded. I am thinking it is in the throttle, the sensor, or the ETM. I towed it to the shop. They are not Volvo specialists. They tell me there is not good compression in two cylinders and most likely bent valves. This is not consistent with my experience. After the first failure it resolved and runs beautifully. Then it threw the code again and has not resolved.

Is there any condition, like limp mode where their compression check would fail? After reading a bunch of these threads, it sounds like an electronic issue. I feel like I want to go get it and fix it myself.

What are the diagnostic steps?

Thanks

[abscate]

You almost always get the ETS light on when the throttle body fails.

If you put oil into the cylinders and then read low compression , you need a valve job Or new engine. It's a pretty good diagnostic.