P0135 Honda Civic 06, install new but worse mileage vs no HO2S at all

Question

Hi, requesting your assistance on this please. I got a code P0135 and replaced the HO2S b1 S1, the code was erased. I noticed that my fuel consumption is worse using new HO2S than having no primary O2 sensor at all. With HO2S I have 6-7km/L vs no o2 sensor of 10-11km/L. Now I'm using my car while the HO2S is installed and acts a as plug only since it is not connected to the ECM. Can you please share experience to troubleshoot this?

Answer 1

P0135 A/F sensor heater malfunction Sensor 1

That's correct, P0135 what happens it is a circuit high it is the same as leaving it disconnected. Check the fuse for this it should be listed as fuse no. 11 F1 SUB. it that is good replace the SUB relay

​ Make sure you have properly torque down the 02 sensor, it can set a P1167 or a P0135.