My non-turbo wagon is slamming down the gas. I put in new plugs, wires, cap,air filter. My check engine light as been on for some time now. A scan test found the following codes: P0133 02 SENSOR CIR. SLOW RESPONSE, P0130 02 CIR, P0400 EGR FLOW, P0120 TPS CIR A. Are any of these codes contibuting to my poor mpg? I have 180,000 miles on this ride and would love to keep her going to 200k. Thanks!

 

My vote would be for the O2 sensor. The computer uses this reading to set the air/fuel mix.

 

Thanks. Are there two O2 sensors? Which sensor do I replace? Is the special wrench that iPd offers worth it?

 

What are your mpg numbers? What kind of gas are you using?

 

I have not checked my mpg for sometime. My car sat most of the summer as I rode my bike to work. I just filled the tank this morning with 87 octane. I reset my trip so I could check mpg.

 

Since the car was sitting for a while, I would erase all codes and see what pops up again. It's kinda clear you will have an issue with the O2 sensor.

I would also check the wires to the O2 sensors and try to run diagnostics on them first.

 

The front O2 is the one that adjusts the air/fuel mixture.

Premium fuel is recommended, I get better MPG with premium.

Also check the ethanol content of the fuel you are buying.

 

I would also check some easy things as well -- holes in the exhaust pipes? Incoming Air connections, especially MAF (Mass Air Flow). Vacuum hoses loose?

Before you throw parts at the problem, do the checks/diagnostics first. Electrical connections?

Burn up the fuel, and fill with premium from a name brand and re-scan for codes.

 

Thanks for the suggestions. Now I have a starting point!

 

I also vote for the O2 sensor, but will throw out a word of caution--the code for O2 sensor sometimes comes on arbitrarily. I have had this happen a few times and have had the sensor looked at by a certified mechanic each time, who has said it is completely normal and that 850s are notorious for false O2 sensor readings.

If the O2 sensor is really bad, the CEL will come on again with the code for O2 sensor (and by again, I don't mean six months later out of the blue).

I usually use 89 octane in my 850 and have found the car runs and starts better with it. I don't notice any difference between 89 and 93 (which I've used as well) but have noticed a decline in both performance and mileage with 87.

Also, does anyone have experiences with different brands of fuel being better? I recently switched to Gulf and have been getting 1-2 MPG better each time.

 

It is just a 7/8" I've just used a open ended 7/8" to get mine off if urs is rusted on get a deep 7/8" socket cut the old wires and it'll come off with ease
You main need to replace the first o2 the second one checks the efficiency of the cat and first o2 but does not alter a/f ratio from what ive heard

 

Usually o2 sensors cause poor mileage. Does the car reek of unburnt fuel?