Service engine soon light is on

my nissan quest 2006 “service engine soon” light is on, went to midas but they said the 2 sensors has to be replace, just told them i will come back, the parts itself will cost me about $800, just the parts itself, but i was not convinced after reading some articles in the internet about this problem, i am planning to go to nissan dealer and get a seond opinion, do you think the sensor is really causing the problem? anybody has comments on midas on how really accurate they diagnose a car problem?

There are no DTCs that say any specific sensor is bad. There are some that say a particular sensor is probably bad, and there are some that say a particular sensor might be bad.
The correct procedure is to follow the trouble shoot chart for each code. That will get you to test the wiring and maybe some mechanical things. Often people replace a perfectly good sensor because it is doing it’s job and telling you that something is wrong with the thing that it senses.
It seems unlikely that two sensors would fail at the same time. Please get the exact five character OBDII codes and post them here. Then you can be better help.

The service engine light will come on when something is wrong according to the inputs to the on board computer. There is a connector under the hood for a code reader, it will give a code to indicate what the problem is. That is the prime diagnostic tool, when all you have is a check engine light. You need to get the codes to know what might be wrong. Your dealer should be able to give you those codes, in fact so should Midas. Midas is notorious as far as I am concerned with giving out false diagnosis, and high estimates.

They said two sensors need replaced. Since we dont know which sensors, I’ll just go out on a limb here and believe you’re talking about oxygen sensors. Original equipment at the dealer will run you just under 200.00 each. Much cheaper than 400.00. The labor to install two sensors on this vehicle involves about one hour. I would try an independent shop instead of them as their history is’nt all that swell. You can also go to a parts store and have the codes read and post those codes on here and we’ll be able to help you better.

There are quite a few sensors on your car, and you didn’t mention which ones that Midas wants to replace.

There are 4 Oxygen sensors.
A Knock (Detonation) Sensor.
A Mass Air Flow Sensor.
A Crankshaft Position Sensor.
Plus lots of others.

You’re going to need to be specific.

BC.