ramseybd6

I recently bought a 1997 honda civic DX. It failed smog and gets poor mileage (29 mpg). Check engine light came on, O2 sensor slow to respond bank 1 sensor 1. Replaced O2 and no difference. Took the car to Honda and they said bad O2 sensor, so I purchased one from them and installed it. Still the same problem. The car also seems to bog down between 2500-3500 rpms which the smog shop also noticed while it was on the machine. The smog guy commented that when the engine bogged down the CO went up considerably. I have also changed out the map sensor and spark plugs and that did nothing. Any help or ideas would be appreciated.

Former User

Also change the plug wires, cap, and rotor and set the ignition timing to spec using a timing gun.

What specific OBDII O2 sensor is being thrown? This code could be due to a problem with the wiring or even the ECU.

ramseybd6

The code was bank 1 sensor 1 which is the O2 sensor on the manifold. I first replaced it with a cheap bosch unit but when I took it to Honda afterwards they said replace the O2. So I bought a genuine honda O2 and installed it but that did not work either.

Former User

Code P0133, right?

You probably have an exhaust leak.

ramseybd6

I do not hear an exhaust leak. Would a very small leak still cause this problem and if so how do I locate the leak if I can not hear it? Would a bad catalytic converter possibly cause this problem?

Former User

A small leak could cause this problem. Start by checking for a crack in the exhaust header and a leak from the header gasket. Then work your way down the exhaust system to the secondary sensor.

ramseybd6

How do I detect a leak that I can not hear. Soap and water or snoop would not work because it would evaporate too quickly.

Anon51

have you tried to do a tune-up?

does the cel come on immediately after you turn the car on or does it take a while?

Please find out the code.

also why are they hooking a smog machine to your 97 DX? it should be an OBD2 Inspection which hooks into the DLC port on your car which is connected to your ecu.

not trying to stray from the problem but 29mpg is a whole lot better then what i get :/
5-10mpg give or take.

ramseybd6

I did replace the spark plugs and map sensor aswell. I will replace the plug wires, cap and rotor and the coil today. The mileage used to be 34-36 mpg before the cel started coming on.

Former User

An exhaust leak near the primary O2 sensor would also reduce gas mileage. Replacing ignition system components is always a good idea to keep the engine running well, but is unlikely to solve the O2 sensor code.