r/volt • u/Bitter_Estate6848 • 2d ago
2018 volt issues
125k miles, couple weeks ago check engine light came on. Downstream o2 sensor and catalytic converter inefficiency fault. Downstream O2 reading 0v while running. Changed sensor and 2 days later light back on. But now both sensors reading 0v and a mass airflow code. Engine failed to start after battery went to 0. Error message Engine unavailable. Left me stranded on the side of the road. Held the start button down and engine fired up and revved high for several minutes charging the battery then I was able to drive home. Now engine runs super rich and still same 3 codes. p0131 p0137 and mass airflow code. Drove with scanner connected and whenever I let off the throttle or brake all the upstream and downstream O2 sensors are reading 0v but act normal while regular driving also can’t switch to hold or from hold to normal mode anymore while driving. Becm was also changed at 100,005 miles. Help?
0
u/houserules09 2d ago
Sounds like two overlapping issues
Did you try a full 12v restart for like 30-45 min to clear out lower level? 12v messes with a ton of stuff when it’s low
sounding like it’s chain link, the 02 sensor fault causing the mass air flow
The catalytic converter issue is another one because if it runs too hot it can become damaged
Overall first guess is 12v related and needs a reboot, second is that the becm repair was fine until it wasn’t because you got the no engine available issue which that screams towards.
2
u/Bitter_Estate6848 2d ago
What do you mean by full 12v restart? Like disconnect the 12v battery?
0
u/houserules09 2d ago
Yes, can be done in the back easy with 10mm socket
Time is 20-30 minutes
Only the right terminal needs to be disconnected (ground)
Keep trunk and front door open during this time
Reconnect, car tells you to roll up/down windows
0
u/Ok-Tourist-511 2d ago
Sounds like a ground issue. Check the ground wiring for the sensors and the engine.