CEL and bad CATS goes on and off
Thread Starter
Senior Member
Joined: Mar 2008
Posts: 295
Likes: 5
From: Fort Washington, MD
2008 C300
CEL and bad CATS goes on and off
So the dealer told me I had bad CATS. I noticed that after putting Techron Fuel cleaner it would go away after the tank was done. It happened 3 or 4 times. Turns out it wasn't the Techron that made it turn off. It was Wawa gas. What is so different about their gas? Am I crazy?
Super Member
Joined: Apr 2010
Posts: 705
Likes: 55
From: LA LA Land
'08 C300 MM Pano
So the dealer told me I had bad CATS. I noticed that after putting Techron Fuel cleaner it would go away after the tank was done. It happened 3 or 4 times. Turns out it wasn't the Techron that made it turn off. It was Wawa gas. What is so different about their gas? Am I crazy?
I've had P0420 & P0430 codes a couple of times (whch are defined as "Catalyst System Efficiency Below Threshold (Bank 1)" & "Catalyst System Efficiency Below Threshold (Bank 2)"...
As for gasoline, I have not attributed it to one brand of gasoline as of yet, mostly, I use Costco gas which is rated as a "Top Tier" gas and they claim "contains five times the EPA detergent requirement"...
Which basically has the same effect as Chevron Techron, but may be I will try out a bottle of that stuff to see if it makes a difference.
Super Member
Joined: Apr 2010
Posts: 705
Likes: 55
From: LA LA Land
'08 C300 MM Pano
So while additive might not clean the catalytic converter, they do impact the readings that will trigger the check engine light if they are out of balance.
That said, there are other causes that can trigger the same code I posted above:
- Three way catalyst converter Bank 1
- Exhaust tube
- Intake air leaks
- Fuel injectors may be faulty
- Fuel injector leaks
- Spark plugs may be faulty
- Improper ignition timing
- Engine Control Module (ECM)
Which really, makes this quite the headache to try and diagnose!
