05 Accord Gas Mileage

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Oct 3, 2012 | 04:57 PM

#11

jcw

Thread Starter

Joined: Sep 2012

Posts: 7

I asked my mechanic about checking the brakes and he did that about a month ago and they were fine.

Oct 3, 2012 | 05:12 PM

#12

shipo

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Joined: Aug 2012

Posts: 3,070

From: Southern New Hampshire

Quote:

Originally Posted by jcw

Update: I talked with the service advisor at my closest Honda dealer (50 miles away) and he could not be convinced that an o2 sensor could be bad without giving a code. He talked me into a BG fuel induction cleaning. I had this done last week ($138) and the car runs a little smoother and seems to have better acceleration but my first check of fuel economy only showed a slight improvement (27 mpg). My local mechanic said that he can replace the front o2 sensor with one made by Denso (as recommended above) for around $110. I'll probably try that next.

I would have strongly recommended against the BG service; IMHO it is simply a cash cow for the dealer and provides no tangible benefit for the owner of the car.

Oct 22, 2012 | 10:27 AM

#13

jcw

Thread Starter

Joined: Sep 2012

Posts: 7

Update:

After:
1) Tune up
2) Transmission fluid change
3) Double dose of fuel system cleaner
4) BG fuel induction service,

the mpg had not shown any improvment. I had the front O2 sensor replaced ($125 part and labor) and have just returned from an 1,100 mile road trip. Going an average of around 70+ mph on the highway I got 33.6 mpg! Problem solved. Thanks to shipo for the original diagnosis, Dr. Driveability for his assistance, and Roader for the name of the OEM part.

The moral of this story: Just because the car is not showing a code does not mean everything is working correctly.

Oct 22, 2012 | 10:35 AM

#14

JimBlake

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Joined: May 2006

Posts: 18,398

From: Wisconsin

Thanks for posting the end of the story.

O2 sensors can get "lazy" & they'll be like that (not bad-enough to throw a code) for quite a while before they get so bad they set off the CEL & error code.

Oct 22, 2012 | 11:21 AM

#15

shipo

Super Moderator

Joined: Aug 2012

Posts: 3,070

From: Southern New Hampshire

Yup, as JimBlake wrote, thanks for updating us; chalk up yet another bad O2 sensor which didn't throw a code.

Oct 24, 2012 | 07:27 PM

#16

accordfan

Member

Joined: Dec 2006

Posts: 105

From:

ok...perhaps a silly question.

What is a bad O2 sensor doing, or not doing, that causes the drop in MPG?

Oct 25, 2012 | 04:39 AM

#17

shipo

Super Moderator

Joined: Aug 2012

Posts: 3,070

From: Southern New Hampshire

Quote:

Originally Posted by accordfan

ok...perhaps a silly question.

What is a bad O2 sensor doing, or not doing, that causes the drop in MPG?

The O2 sensor is the computer's main method of fine tuning the air to fuel ratio when in closed loop mode (i.e. a base fuel map is used to approximate the correct ratio based upon the density of the inake air, and then the O2 sensors are used to confirm the setting or to make adjustments). If one or more of the sensors are delivering faulty readings, the computer makes incorrect adjustments.