Rep Power: 0

Around 6 months ago i bought a civic 2004 LX d17a1 that had the check engine light on

I went with a mechanic that checked the code with a scanner and it was the O2 sensor bank 1, i bought one brand new o2 sensor from autozone and it wasnt compatible so i bought a DENSO sensor that was functional

the mechanic did the swap of the sensor and it seemed to work fine but for some reason after a while of running the same day the car the check engine went on again, After that i junked one old sensor from another honda civic and the same result, the mechanic checked the wiring, the voltages and deleted the code every single time and it seemed to come more faster when the car was at functional tempterature.

for some reason the o2 sensors give readings when the error code is deleted but after a short period of time the o2 sensors stop giving readings and they just flat on a value.

the reason i was concerned by the error code was because the car MPG was to low at around 11 to 14, the car has around 400k km on it, but it seems excesive consumption and it has a rough idle.

for the time being i think it could be a clogged catalytic converter because the car wont go past 100 km/h or 4500k revs (i dont know if the fact that is a non-vtec affects this) and this may overheat the o2 sensor i think
or an error in the computer but is hard to test given the prices of the parts mencioned.

 
Rep Power: 367

unbolt before the cat and see if it improves - this should bypass the cat by throwing exhaust directly to atmosphere. it will be loud, just temporary test

 
Rep Power: 222

What's the actual code number?

 
Rep Power: 0

Hello guys, i have discovered the solution to the multiple issues listed.

First of all the sensor malfunction is caused by a ground cable that is malfunctioning.

Second i had a blown head gasket that caused overheating and poor gas mileage so it was somewhat solved mpg wise.

Third the acceleration issues were also solved up to some extend, i have indeed a partially clogged catalytic converter but most of the issues where caused by the headgasket leak.

on rewards to the repair it went to upwards of 700 usd which is a lot since i live on mexico
and they had to rectify the block, the head, solder cylinders que all sorts of repairs because the previous owner used plain tap water.

now with the repairs and using anti-freeze coolant the car seems to run fine at the moment, thanks for your responses and i hope this to be useful for someone else.

 
Rep Power: 224

Glad you got it sorted. Head gasket failures are very common in this generation.