Bought a 99 civic dx Friday, 98k miles sedan auto, filled it up when got it and set the trip to zero. Today after work I had the much anticipated fill up and mpg calc. Took 10.5 gallons and traveled 341 miles, roughly 32 mpg. Which is expected, according to EPA. Car has check engine light on, code p0135, which seems to be an o2 sensor. Debate I am having is that I'm in line with the EPA estimates, so is it worthwhile to pay for the sensor fix? Don't seem to be able to gain additional economy, are others with similar cars exceeding my mpg? Thanks, new to forum

 

I'd change out the sensor. It'll eventually pay for itself (probably in about a year), but bad O2 sensors will destroy your catalytic converter, which is expensive on a Honda.

FWIW, I do a lot of mixed driving (back roads and backed-up city traffic), and get about 34mpg when I drive it like I stole it. Out on the highway, I'm around 36-37mpg.

 

If there is something wrong that the car is telling you, yes, you need to fix it before something else breaks. Please do not ignore things like that unless you want to throw more money at the car later.

 

Thanks for input, I should have mentioned that the driving was approx 90% highway so perhaps the car may be able to achieve much better mpg if sensor is fixed. I was thinking I was doing good by doing slightly better than EPA estimates... I def wouldnt mind getting in the 35 mpg range. I'm excited about owning a civic!!!! I had been looking for a good deal on one for couple months... Thanks