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P0430 Catalyst System Efficiency Below Threshold Bank 2)


MUDGUTS
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Hi,

This fault code (P0430 Catalyst System Efficiency Below Threshold Bank 2) has been coming up on my 2004 GS300 for nearly 6 Months / 8 thousand miles. I'm getting consistently good mpg (27-30) and the car went through its MOT after the code first came up, obviously passing its emissions part of the test. Sometimes I can go 1500 miles between it coming on, sometimes only 50 miles  

My fault code reader allows me to reset the MIL which I do each time it comes up and also read the Freeze Frame Data which is below.

DCTFRZF                    P0430
FUELSYS1                  CL
FUELSYS2                  CL
LOAD_PCT (%)           71.4
ETC (F)                        189
SHRTFT1 (%)              3.1
LONGFT1 (%)             -3.1
SHRTFT2 (%)              0.8
LONGFT2 (%)            -1.6
RPM (/min)                 1704
VSS (mph)                  46
IAT (F)                         52

I'm interested in a decoding of the info above if anyone can help. 

 

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sounds like your Oxygen sensor needs replacing. you can test this by swapping the working sensor from Bank 1 to Bank 2. if the message registers on Bank 1 after the swap then you know you have a faulty/dead oxygen sensor. if you still get the fault on Bank 2 after the swap your Bank 2 catalytic converter might be faulty. most of the time it might need cleaning using a product i used called Cataclean. although this did not clear my check engine light most reviews i read confirmed it did in their case. i had to replace my sensor and the check engine light cleared.  if you need a new Denso sensor order from rockauto.com worked out £35 for the part and £13 import duty for royal mail = less than £50 Lexus wants over £100 for the same sensor. took about 2 weeks for econo delivery.

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Thanks Gents. I'll have a look underneath to see if I can swap those post cat sensors. I replaced both the pre cat sensors last year as the heaters in each had failed. 

From what I have read, changing the post cat sensors is a bit of a pain unless I can just cut the old wires and wire the new one in.

What is odd is that I'm going up to 1500 miles at times without a fault code then it comes on several times a week. The only pattern I can see is that when I'm using the car for longer (150 mile) runs the code isn't so regular but as soon as I'm using the car for running around town, after a day or so the code appears.

 

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  • 3 months later...

Hi mate, I had the same problem replaced both cats and 4 sensors at a  cost of  £1200 turned out to be a very slight leak on exhaust after the down stream sensor only picked up on it by chance so replaced exhaust with stainless steel  £575 grand total of  £1800 at least I know my cats won't need doing for at least 100000 miles .

Brian

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