I have a 03 6mt G35. The problems started with bank 1 and 2 sensor 2 (post cat) o2 circuit low voltage. After some probing, it looked like one sensor was bad and the other had a bad connector. Bypassed the connector and replaced the other sensor, cleared the codes, those codes never came back up. Fast forward 30 miles, now I've got a code for bank 1 and 2 sensor 1 (primary) o2 circuit high voltage. It's exceeding 1.3V when I blip the throttle. It seems to do this intermittently. This car has factory narrowband sensors, so it should only see between .1 and .9V. This implies either a short from the heater circuit, or a bad ECU.

Initially I only had a intermittent misfire at idle. After driving in today's rain, it misfires even while driving. It seems to have low power too.

Any ideas?

Before while trying to diagnose the misfire, I thought that it was running rich. I cleaned the PCV, MAF, air filter, and replaced the plugs. After replacing the plugs it initially seemed to rev more smoothly. This was a couple days ago, now it seems reluctant to rev and misfire throughout the rpm range.

B2S2 voltage is now pegged at 2.54V until I drive for a bit. This is a new sensor.

 

any resolution to the problem with the o2...i have a similar issue and suspect a bad ecm ground circuit for heated o2 b2s1. let me know what u found please

 

Guess youve never fixed it. Jm wondering if one of the new plugs are bad or loose or if the throttle body on drivers side isnt opening as expected. Hell maf could be bad too. Over engineered imo. Any ideas people? What sensors commonly fail on the hr motors? Camshaft pos sens? Gonna have to look around and see. Starting to feel like car is having timing issues or torque converter lockup issues.

 

what codes are you getting?

 

when I put in the high flow catalytic converters I had to beat on a Bolt and it broke the resistor inside of my bank 2 sensor 1 oxygen sensor so it was throwing a code for a shorted 02 heater in bank 2 sensor 1. After putting in a new Oem o2 sensor in, code went away and it drives normally. Except that bank2 runs at .9 volts 99 % of the time where bank 1 sensor shows a nice .4 or .5 volts. Feels a Lot like a crazy torq converter locking and unlocking and a mildly misplaced shift or extra gear. Could a bad throttle body or MAF be at fault...or even a cam sensors ir trannh sensor? What sensors are commonly problematic? Mechanically all seems well. Currwntly the only code i get is ?coolant below regulating twmp" cause the tstat is stuck open. Gonna fluah her and put a new oem tstat and water temp sensor in.... already purchased just waiting on time. Any help or past experinces shaed are greatly appreciated. Btw.... sensor 2 poat cat seem to mkrror one another. Should i put in a new oem sensor in bank 1 sen1 to see what feedback new sensors will provide? B1s1 is original.... b2s1 is new.. both post cat sensors are original. Ive read that the O2's are grounded through the ecm and it could have burned the ground path on the PCB... i have access to a non-sport ecm and throttle bodies for some $$ but dont wanna waste it if not needed.

 

Fixed typos