Check engine light code on scanner says 02 sensors too lean. Mechanic did not replace 02 sensor but repaired a vacuum hose.

We should start by replacing the thermostat and then clear the codes and then drive it. Here is a video to show you how to clear the codes and I have included how to change the thermostat out in the diagrams below. Tighten the thermostat housing bolts to 9 nm, which is not that tight, do stripe the bolts out it is easy to do on this car.

https://youtu.be/ahK_eucFi-k

Check out the diagrams (below). Please let us know what happens.

Hi,

Based on the code, it indicates the thermostat isn't allowing the vehicle to warm up fast enough. This is either a wiring connection issue or a faulty thermostat. However, the code is likely indicating the thermostat itself has failed. If the code was P0598, that would indicate a short in the wiring. Regardless, the thermostat should be replaced.

The thermostat is located at the water pump on the lower left side of the vehicle. I attached a couple of pics to help you locate it.

What I suggest is this: Check to see if the electrical connector is tight, in good condition, and if there is no corrosion in the connection.

Interestingly, this is a MAP-controlled thermostat. MAP stands for manifold absolute pressure sensor. This could be tied into the lean fuel mixture.

Try this and let me know what you find. Also, could you provide the other code for the lean mixture?

Joe

See pics below.