I have a code p0420. What chemical products can I try in my gas tank to see if this clears the code

P0420 GMC - Catalyst System Low Efficiency Bank 1 ' Add Comment
Possible causes
- 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
- Powertrain Control Module (PCM)
What does this mean?
Tech notes
As the code description implies the P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.
What does this mean?
When is the code detected?
If a condition exists which causes the Powertrain Control Module (PCM) to detect excessive Bank 1 HO2S #2 activity outside of an acceptable range for an extended period of time, the PCM will set the P0420 code. This indicates that the three-way catalytic converters oxygen storage capacity is below a threshold considered acceptable.
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
P0420 GMC Description
In order to maintain a reasonably low emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx), the engine controls system uses a three-way catalytic converter. The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO present in the exhaust gas. This reaction converts them into harmless water vapor and Carbon Dioxide. The catalyst also reduces NOx, converting it to Nitrogen. The Powertrain Control Module (PCM) monitors this process using Bank 1 HO2S #2. Bank 1 HO2S #2, located in the exhaust stream past the three-way catalytic converter, produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalysts ability to convert exhaust emissions effectively. If the catalyst is functioning correctly, the Bank 1 HO2S #2 signal will be far less active than that produced by Bank 1 HO2S #1.

Agree with Bill's analysis.
Also - fuel injector cleaner in the tank is a complete waste of time and 100% ineffective. There is only one way to clean an injector, and that requires removing the injector from the vehicle. There are no shortcuts.

There are some products which will repair a fuel tank. It depends on the leak.

Some of the products require removing the tank, adding the leak chemical and swirling the mixture inside the tank. Other products are like JB Weld which could work, but there are specific chemicals just for this job.

If you have rust on a 1999 vehicle, it can cost you less to replace the tank new, than to buy chemicals and lose gas when they do not work. Rust is especially hard to guarantee a repair on. Fix one place and another leaks a day later.

Check out the Internet for new tanks. It will be harder to find an old tank because most are ripped off before the Salvage cars are allowed on the lots.

Radiator shops sometimes do this repair.

I hope my solution is helpful.

Mine is a 2001 Sienna LE. I got the P0420 code and the dealer want to replace an engine control computer for $1600. I've found posts that say you can replace your oxygen sensors, which still costs around $100 each. The P0420 seems to be emissions related. When my check engine light comes on, I run the highest grade, no ethanol gas, and usually within a couple of tanks, the light goes off again. The last time it happened about 2 wks ago, I put in the 93 octane no ethanol premium and a can of Seafoam and within a half a tank, the light went out. Your problem might be more serious, and I don't know what the 1150 code is, but so far that's worked for me.

The first thing I advise on this kind of situation is DO NOT just randomly throw money at it. I would never repair a P420 or P430 without turning the CEL off several times and making sure I got the code to come back again consistently. Anything you do to try to fix this issue will be very expensive and it could seriously just be a bad tank of gas. Also, be sure that it is not still covered under your warranty. Some emmission items are covered for 100k or more miles.

First your trouble code:
OBD-II Trouble Code: P0420 Catalyst System Efficiency Below Threshold (Bank 1)

Replace the catalytic convrter

You never replaced the exhaust converter,ruined by the
coolant--- PO420

The P1133 is probably an O2 Sensor also ruined
I would replace them all.

Who ever did the head gasket should have done
all that

Don't waste your money on anything that goes
into a fuel tank,not necessary,nor does it fix anything

please go to the provide link for diagnosis of this code,but the bottom line here is the catalytic converter may be worn out

http://www.p0420.com/

are you running regular gas or not you should be running special unleaded fuel

Hello!

the code you speak of relates strictly to the catalytic converter. it is possible there is a faulty sensor, however that choice is highly unlikely. Catalytic converters carry a 5/50 7/70 and 8/80 warranty depending upoin the state you live in...this may be a repair covered under manufacturers warranty. this code is becoming very prevelant in many auto lines as a result of the insurgence of ethanol dilution of our fuels. the "10%" ethanol sticker is located on most pumps. Most vehicles on the road today are not flex fuel capable and this ethanol is wreaking havoc on our fuel and emission systems, especially the catalytic converters. the converters are caked with deposits from the ethanol, reducing its effeciency. if your have access to well worth branded products (not available in ANY parts store, typicaly dealers and repair shops only) try adding on succesive tank loads of fuel their product called Octi-Plus. this products helps remove ethanol products, and very well may save yoiu big $$$ for that converter repair bill...i hope this helps..check out this link....

http://www.wellworthproducts.com/

ps i appreciate your 4 thumbs up if this helps you!

You Definatelly got some Bad Fuel. Get a can of B-12 Chemtool from any Auto Parts Store or Wal-Mart and Pour it in the Gas Tank then Let it Run for a While. Should help Dramatically! Let me know!