I have two codes p2177&2196 should I replace upstream o2??

 

Why?

 

So the. Ss will run! It run fine in cold mode ,than it misses and stinks.

 

Well let's see here

P2177 - System Too Lean Off Idle Bank 1

P2196 - O2 Sensor Signal Stuck Rich Bank 1 Sensor 1

Possible causes...

- Faulty Front Heated Oxygen Sensor Bank 1
- Front Heated Oxygen Sensor Bank 1 harness is open or shorted
- Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection
- Inappropriate fuel pressure
- Faulty fuel injectors
- Intake air leaks
- Vacuums leaks

Before just chucking an upstream O2 sensor at it, you might want to do a bit of diagnostics, or take it to your dealer or a diagnostic technician.

 

Thank you ,the fuel mileage dropped first , this started when outside temps droped into 20s, when it gets above 35. it ok and runs fine! The colder it gets out the worse it gets.

 

I'd start by having the fuel pressure checked, extreme cold can show up a failing fuel pump.

 

I think I understood it's an SS? If that's correct, lot's of places to look. A couple of fuel pumps, fuel regulator etc.

If you just want to throw money at it, then go ahead and replace parts that are mentioned in OBDII code names. The code names rarely have anything to do with the actual problem. Thus the recommendation to pursue troubleshooting.

 

Personally I would start at the bottom of the list (simplest first) that donbrew posted.

 

Just to let all know it was the up stream 02 the was the cause of misfire all cyl. Low vac to 28" ,little boost, Runs better than it has for a year.