Quiet Exhaust linked to CEL?
 

As soon as I started my car today, I noticed the exhaust was a slightly deeper and quieter tone. It did not sound like it used to.

I drove about 10 miles then the CEL turned on:
PO134 and PO154.
O2 sensor circuit no activity detected bank 1 sensor 1
O2 sensor circuit no activity detected bank 2 sensor 1

Both O2 sensors went bad at the same time. Could that happen? Could they cause the exhaust tone and sound to change like that? Now @90,000 miles.

A little history. Bought the car 2 years ago with PO134 code at 77,000 miles. Reset it and it never came back on. I never replaced the O2 sensors.
2 months ago, CEL light turns on for PO134 while it was raining, then later turns off by itself in the same day.
1 month ago, CEL turns on again for PO134. I turn off the car and come back 30 minutes later and the CEL is gone.
In the past, the exhaust sound did not get quieter or deeper when this CEL code turned on.

Anyone? This thread was only viewed a few times.

What a bummer...your hearing changed exactly at the same moment. Since of O2 sensors are connected to ECU brain, I would imaged they were having troubled in sending data to the ECU, thus you may have been getting lean...only a guess.

the wiring harness (and connectors) could be the problem. Open circuit in the signal or ground wire -- also, the heater circuit could be open.

Sent PM.

Regards,
paul...

If the code came up as being P0101, 0102 or 0103 I'd say that it's definitely the MAF sensor .

I drove about 30 miles so far after resetting the CEL. It did not come back on so far.

Going to drive another 10 miles then try to get the car inspected today. My inspection is due next month. If it passes, then I am not going to worry about replacing the O2 sensors or checking on the connections until I do my enginer oil and transmission oil change in a couple of months.