I got the ECU fault code of 34 and 77. One is Knock Sensor and the other is rear heated oxygen sensor. Which one should I replace first to fix this probelm?

 

i say both.....but im not too experienced with consequences, but IF YOU HAD to pick i'd say knock...jsut wait for more responses....

 

go with the o2 sensor first....i believe its cheaper then the knock sensor, and 50% those knock the knock sensor off (lol?)....i wouldnt replace the knock sensor until after the o2 sensor, because that is a definate error.....reset the ecu, drive around for a day, and then check it again, and if it still says the KS, change it ....i too have tried denying it, but i finally broke down, and am buying one tomorrow (KS) and installing it on saturday.....now i cant buy my friggin y pipe ...fudgin nissan