It is IMPORTANT to note that some situations
(on-board diagnostic) systems
are going to tell you ... the very best information...
From my personal experience OXYGEN SENSORS
merely report the news... So lets say an AUTOZONE
" does a FREE
read on your car...
The car is tossing alarms on the OXYGEN SENSORS...
Save your money... Skip the next AUTOZONE
suggestion to buy NEW SENSORS...
The new SENSORS will only complain EXACTLY
as well as the old ones... (don't buy them).
I am going to take a WILD STAB here and suggest you
can take your car to an EXHAUST SHOP
They will likely focus on BLOCKED EXHAUST
Mine was a CATALYTIC converter... but a MUFFLER
baffle will also cause popping, backfires... and check engine codes...
Worse... an EXPLOSION
(more likely minor... but who knows (urgent in my opinion)).
Check out your EXHAUST ELEMENT PRICES on
Amazon, eBay and/or Rockauto (for your location)...
BEFORE going into the EXHAUST SHOP...
This is a job that is not terribly EXPENSIVE if you
know enough to keep the PRICES COMPETITIVE.
ALL else fails... complete systems are available on-line
(just be sure you comply with ALL LAWS
Hope I'm helping
Carnac the Magnificent