My son's 2015 GS 350 showed this codes when I did a scan. What does this mean? Does this mean bank2 sensor is bad? On a GS 350, is it DIY friendly to fix it myself?

 

A P0430 means the catalytic converter on bank 2 is failing. On your GS 350, this is not a DIY job. It requires a lift and professional tools.

 

Thank you for the help. I guess I'll have to take it to the shop then.

 

How many miles on it?

 

It could be as simple as a sensor or as involved a catalytic. Best to have someone do a full diagnostic as it isn't always the catalytic that will be the root cause the fault code. Here's a helpful thread: https://www.clublexus.com/forums/gs-...and-p0420.html

 

It is true that the root cause needs to be fixed if it comes down to cat replacement. It can be tested or checked after some cleaning. After that cleaning application, you can check how long it takes for 0430 to return. If lucky, long time.

But mention your miles, any other conditions, etc.

If you have OBD2 device, you can watch some videos on this topic and compare you short and long term fuel trims, and the 02 sensor readings.This is something mechanic will check. Mechanic will also check for pre and post cat temps, leaks etc...

In a honda van, for example, crappy vcm causing oil fouling is the root cause of multiple cat bank 2 replacements. If CARB, its expensive. Either way, 0430 final fix is cat replacement if nothing else is helping. I have to replace that cat soon and its CARB. My 0430 returns quickly.

 

No, it doesn’t mean that. You have likely been TOLD that by a person or source you thought you could trust, so it’s not your fault you think that - please do not interpret me as being harsh towards you. It’s important to understand this: what that code means is the ECU is not seeing the voltage value, or timed voltage behavior, from the Bank 2, downstream 02 sensor, that it expects to see. That is ALL that means, and that general situation is true for almost all codes. It is a clue, but not a diagnosis.

The most common causes of this are an air leak in the exhaust, or a bad/worn/dirty sensor. Cat is a less likely cause. It is important to do a full diagnostic and go through the complete differential diagnosis of various causes of a bad signal and not just swap parts instantly. A lot of people waste a LOT of money on new cats, then find they have to go to the muffler shop to have the air leak fixed. Big disappointment, big waste, and I’d like to help people avoid that!

^^ Good advice/response.

 

Also note that you will end up with multiple codes where one of them is specific to sensor (the two visible from the front when hood open). 0420 is the downstream and very common. Many will also tell you to run cataclean or equivalent, and is a temp fix in case you have to do a smog etc. But this is normally discouraged. Air/vac leaks usually are 0442 or whatever we get continuously on our camry/avalon. Make sure to watch couple videos (South main auto, Eric the car guy etc) with detailed diagnosis for 0430. There are many other videos. Even if you go to mechanic to get checked out, some knowledge helps.

0420 and 0430 are very broad with many causes.

 

A lot here is speculation at best. Depending on the miles, climate (rust underneath), fuel used etc. The link AJLex19 posted is going to be the most valid route at this time to start with.

Cat cleaning works if you know what you are doing with the process and the light just came on recently. You can resolve it completely. Knowing the miles, climate, and fuel used would point out a better starting direction. Or if to look for a exhaust leak (rust)? Let see what the op says 1st.

 

 

About 194,000 miles