1999 Honda Civic errors

Hi HARIS109,

P0135 = Primary HO2S-1 heater circuit malfunction.

P0172 = System too rich

P0141 = Secindary HO2S-2 heater circuit malfunction.

P0135 and P014 indicates both the heater circuit of the O2 sensor is faulty. I will send the diagnostic files to you.

As to the fuel trim too rich, P0172, it could be due to the faulty O2 sensors so primary concern is to get the O2 sensors problem rectified first.