I have an 1990 Accord EX. The O2 sensor needs replacing, but I was wondering if this is really needed? Does it effect the performance of the car?

 

How do you know that it needs replacing? Usually, if your O2 sensor needs replacing, you will get terrible fuel economy until you get it replaced. The O2 sensor analyzes the exhaust gas and tells the car how much fuel to mix with air. When the O2 sensor goes bad, the car just dumps a lot of fuel in, and you end up with unburnt fuel going out your exhaust, and wasting the fuel.

How do you know that it needs replacing?

Check out www.oxygensensors.com for cheap replacements.

 

A lazy O2 sensor can indeed effect performance.
It can effect not only Fuel Efficiency (Milage), but can contribute to Hesitation and Surging as well.

With regards to O2 sensors and other Engine Management components be careful. Too cheap can become very expensive.

If you insist on Aftermarket, stay away from the "universal" types which require you to cut and splice; such as Bosch.
For Honda / Acura I'd suggest either Genuine Honda or Denso as an alternative, and they should be "Plug & Play".

P

 

I know my O2 sensor is going bad because I was told it was. Yeah, I'm getting like 20mpg city and and like 25mpg on highway. Aren't accords suppose to get more than that?

 

The Twin Cities in winter?
I'd say you're not doing bad, considering the artic conditions and such. Let me see if I can chase down the EPA ratings for your ride.

As a real-life comparison, I had to change out my primary O2 sensor last month because of a sensor heater failure. And although I didn't notice a rousing increase in performance, I surprisingly picked up 4.5 MPG. Honestly, it was long overdue for change-out; the car has 225,000m on it.

Here's an Oxygen Sensor Primer you may find interesting:
http://www.autohausaz.com/honda-auto-parts/honda-emissions-oxygen-sensors.html

P

 

EPA ratings for 1990 Accord EX = 23 MPG combined.
http://www.edmunds.com/used/1990/honda/accord/3875/prices.html

I've seen higher.

P

 

Is that rating for city or highway? My car is getting there too. I have aroulf 197,000 miles on it and I do need to get the O2 Sensor fixed. Hopefully it will improve my car's performance gas-wise.

ALSO, AFTER I REPLACED THE SENSOR DO I HAVE TO RESET ANYTHING?

 

sometimes when the o2 sensor light comes on , it might
mean your catalytic converter might be bad instead
just thought id let you know so you dont buy an o2
for no reason...

 

If there was no corresponding "Check Engine" lamp displayed for the O2 sensor then NO; you will not have to reset, reprogram or sprinkle Holy Water on anything after replacing the O2 sensor.

ALL EPA ratings are an average of City/highway driving. Let me see if I can find the test ratio.

P

Here you go:

[quote] "The Fuel Economy number is the average combined number of miles a vehicle is able to travel using one gallon of fuel according to EPA simulated laboratory tests that consist of 55% highway and 45% city driving conditions." [quote]

 

This is true on 1996 and later OBD2 vehicles (all manufacturers). It is specifically the function of the secondary O2 sensor mounted downstream of the Catalytic Converter.

This gentlemen's car (1990) is an OBD1 vehicle which does not incorporate the 2nd O2 sensor and thus does not have the capacity to monitor Converter efficiency.

 

I think mine might be going out too. I have 185k miles on my car, and since about the last 15k, I have noticed that my fuel economy have gone down a bit. These last 2 fuel fill ups, I got terrible gas mileage. If it happens for 2 more tanks, I will definitely go ahead and change my O2 sensor. Back in the day, I used to get 31-32 MPH interstate driving. In the last year, I am getting 30-31MPG. My last fill up, I got 26 MPH.

 

Thanks for all the help guys. This has been a great place for me to learn new things. Other places either just BS a lot or they don't help you at all.

 

Glad you found it informative.

P

 

I recently changed my O2 sensor for a bosch plug and play ,
it helped my fuel mileage a lot , but after a week or two i lost the mpg i gained and got
cel light again.
my question is could it be a bad O2 sensor (cheap) or the cat is having the issue because i took to long to replace the sensor.
Accord 94 ex 255.000 miles.

 

I would place my money on it being the Bosch sensor. They are know for doing this when used as a replacement HO2S. But to be sure you should have the DTCode scanned.

FYI On a 94 Accord you could retrieve the ECU codes yourself. Are you aware of the Self Diagnostics SCS connector short technique that will get the CEL flashing codes?

 

Thanks for your help , yes i've read about the cel flashing codes i will try it tomorrow.
Is it true that the cel light needs to be on to pull out the code ,because i get the cel only in the mornings.

 

If you only get it in the AM then that is when I would jump the SCS connector just to be sure you get the code. Sometimes the CEL is not stored in the ECU, some people refer to this as a soft code. It will only be traceable at the time the CEL is on. So keep a paperclip handy.

 

I got the code it's # 43 fuel supply system.
I'm taking it to my mechanic tomorrow to check the pressure in the fuel system.
although what i read it can still be a bad O2 sensor.
have to wait till tomorrow.