Check engine light flashing

Codes were reading misfire on 5 and 8 , left and right bank cat converter. Spark plugs are good. Coils were replaced. No vacuum leak detected. Fuel injectors cleaned. Check engine light still flashing but only code is right bank catalytic converter. Truck has never ran rough and runs fine. Would a bad catalytic converter cause it to flash. Everything I read is misfire but the truck is not misfiring

 

Define good? Look good? Recently replaced?

Have any specific code numbers for all this?

 

A flashing check engine light is usually a chronic misfire.

and like the guy above me said define good when talking about plugs

 

What brand coils did you install when replacing?

 

Misfire on cylinders #5 and #8 at idle or during acceleration?

 

Plugs are Toyota plugs and have less than 20k miles. 3 mechanics looked at and all said they were good. Codes were P0300 P0305 P0308 P0420 P0430. Now only the P0420 comes up. Misfire codes do not come up currently. Truck does not drive like it's misfiring. Not rough at all. Not sure the brand of coils.

 

Just making sure you didn't end up with counterfeit plugs from scamazon or something. Can you clear all your codes with a scanner or by disconnecting the battery then drive again and see what codes come back?

Welcome from KY as well. Whereabouts are you located?

 

Only the P0420 comes up after clearing the codes. But check engine light still flashes. Also, it only flashes maybe 7 to 10 times periodically, not all the time and only on the expressway after reaching 60+ mph

I'm in Louisville. Whereabouts are you?

 

I'd suggest clearing it then driving it a few times and letting it flash a bit and check your codes again and see if you get anything different.
I'm in Etown

 

That was done. Still flashes and only code that comes up is P0420

 

the ECU detects whether the cat is working efficiently by taking a delta of the readings coming from the upstream and downstream O2 sensors. I've probably seen more times when the O2 sensors on the impacted bank were the problem than the cat, so that's where I'd be eyeballing. More on that in a couple paragraphs....

If you bought any of your ignition parts (coils, plugs) off fleaBay or scAmazon, there is a very high likelihood that's your problem: You got counterfeit parts, as mentioned above. This is absurdly common!

Flashing CEL in layman's is just "There's a major f'n problem" whereas solid CEL is "yeah, soemthing inconsequential isn't working".

Want to do a knuckle-buster test? Swap your upstream and downstream O2 sensors from bank1 to bank2. Does the cat efficiency code change, saying the cat on bank1 is now sub-par? If so, replace both O2 sensors you moved to bank1.

I didn't think you'd get a flashing CEL from clogged cat, but ... I guess you do?

 

Much appreciated..... I should note the catalytic code I've had for more than a few years. So I'm sure the cat is bad.

 

This worked for my Camry

https://youtu.be/TxUya70kkQk

 

It takes a lot to clog up a cat. If you weren't actively running rich, or similar action which would send a lot of crap down into the cat, I'd still try the left-right swap of both O2 sensors. You'd be surprised...

 

I assume you removed the spacer before smog?

 

Nope, has passed smog 3x with this fix - In California.

If I remove it, the code comes back hahahaha

 

Update on the misfire codes. Replaced both cats. It needed it. Truck runs much better. BUT, I'm still getting the occasional flashing check engine light for misfire. Any ideas? I'm thinking purge valve fix or replacement. Thoughts? BTW, truck runs fine. No issues besides the flashing check engine light

 

when it flashes, count the flashes and it'll tell you the code.

 

I've counted. Sometimes it'll be as few as 3 and as much as 11. And everything in-between. Some rides it won't flash at all

 

Still getting codes for the same 2 cylinders misfiring? Don't think you ever said where the plugs came from or what brand the coils were.

 

This was my next question.

@Ctundra, other than letting us know that, you also need to be watching which cylinders are misfiring - is it still 5 and 8? - and if yes, swapping the coils from adjacent cylinders 6 and 7 to 5 and 8 doesn't see the code change?

 

I had a similar issue on my '02, but I have the 3.4L v6. P0420 code and Chronic flashing check engine light with misfire code(P0300 and I belive P0303). Even after replacing the cat the misfire codes persisted. Unfortunately, it ended up being a blown head gasket that was causing the code. You can also check out a video from "Toyota Maintenance" on YouTube who diagnoses the misfire code (I believe it was P0303) in a 1st gen Tacoms and walks through how he determined it was a blown head gasket. Not sure if it will be the same for the 4.7L, but it seems like similar symptoms.