('06 XC90, 2.5 L5 Turbo w/153k miles) Tell me if you have heard this one before! I have read all the threads on here about this warning message and yellow triangle but my symptoms don't match up to any others. It started out with a slight RPM surge at idle, or coming down to idle, and was so slight you could not see a deflection of the Tach pointer. The car would stay running. It has never shut off. It has progressed to an RPM surge of 200-400 RPM's happening at the same time, either at or going to idle and has given me the warning message and yellow triangle. Again the car stays running. Hooked up my VIDA/DICE unit and got the following codes;
ECM-120D Air mass - Signal too low (red light)
ECM-121B Mass air flow sensor - Flow too low (yellow light)
ECM-216D Long-term fuel trim, Bank 1 - Signal too low (yellow)
ECM-21E0 Long-term fuel trim, Bank 1 - Faulty signal (yellow)
CCM-0061 Damper motor internal fault (yellow)
CCM-0062 Damper motor, temperature left internal fault (yellow)
CEM-9C03 Antenna/light ring signal missing (yellow)

What I need help with is, do any of these codes equate to what the engine rpm is doing? I am retired on a fixed income and don't want to "throw parts" at it in hopes of accidentally hitting the bullseye. Thanks All !!!

 

If you have Vida you can click on the codes and Vida will give you suggestions as to what can cause that code to appear - for your 120d code - this is what appears -
Click signal too low and links appear telling how to check all that stuff.

 

Thank you for the reply hoonk. I will check it all out in the morning, after coffee!

 

UPDATE - Checked out all of the possible causes for the engine rpm surges. MAF sensor is new and clean. Throttle body is clean also. Checked out all of the air inlet (black plastic) piping I could get to from the topside of the engine. It all looked good. I want to get it on a lift and look at the bottom side later. Emptied a can of carb cleaner on just about the whole engine while it was running and got no change in rpm's. I plan on changing plugs and the bank 1 O2 sensor. Those are easy and won't hurt the wallet and just might be the solution.

 

Final Update - After all this time and many, many forum posts readings, I took a shot at the cheapest fix and got lucky. On my '06 XC90, 2.5L, FWD I replaced the Bank 1 (upstream of cat conv) Oxygen Sensor and the codes have went away and the car is running much smoother. While getting to the actual sensor was easy, the electrical connection was not. If you have small hands you could possibly disconnect the plug from underneath the car without taking the wheel off, but with my neanderthal build it was much easier to get to with the left front wheel off. I took some pictures of the connection but they did not really do any good. There is a white locking tab that holds the connectors together. I was able to get a long flat tip screwdriver under it and pivot it up towards the front of the car. This "unlocks" the connection and from there it is a matter of getting your hands in there and pulling the two apart.