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Greg
Greg, Import tech
Category: Lexus
Satisfied Customers: 5732
Experience:  17 year shop owner
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Lexus LS430: Lexus LS430 The VSC - trac off and engine check

Customer Question

Lexus LS430 The VSC - trac off and engine check warning lights are on - occassionally they go off but come back on. What is the problem?
Submitted: 1 year ago.
Category: Lexus
Expert:  Greg replied 1 year ago.
Name isXXXXX goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back,

Can you take a trip down to AutoZone and get a free code readout done ,
I need the malfunction codes to help you sort out this issue .

The VSC and trac off light come on automatically when the check engine light comes "ON".

Will check out the post tomorrow for your codes you have from Autozone ..

Kind regards Greg
Customer: replied 1 year ago.

The code is P420. One 02 sensor was replaced cost for part $226.00

Expert:  Greg replied 1 year ago.
Hi Frank ..

This code does not really mean the O2 sensor is faulty , the sensor is one of a few sensors that should be tested and checked before replacing any of them .

You may also just have a leak in the exhaust system that is giving a bad reading to the
sensors and causing the code to trip .

In most cases its the TWC catalytic converter that is at fault .

A good scan tool is needed to do a proper diagnostics to see where the fault lies
in your case with this code I've seen people just about replace all sensors and still not repair the problem, end of that story was he had just a leaking exhaust .

And in your case $226.00 due to bad information as many think one code one sensors , the code could mean anything from a MAF sensor ,crank sensor,IAT sensor and many other sensors needed ..

I suggest you find a good repair shop that has experience with Toyota and Lexus
or the dealers to do a complete test on this issue ,you will save money in the long run .
My goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back with the reply box below and not the poor or bad service button ,

For further assistance there is no extra charge after accepting.

Rgds Greg
Customer: replied 1 year ago.

What is the TWC catalytic converter?


Does this code (P420) refer to any particular bank?


Also what do the sensors cost and how many are there?


This one was not from a dealer

Expert:  Greg replied 1 year ago.
Hi Frank.

okay the TWC is the catalytic converter (Two way converter).

the P0420 is the bank 1 and the P0430 is bank 2 .
Bank 1 being the side with the #1 cylinder

There are 4 sensors two upstream A/F sensors and two down stream o2 sensors ,

graphic

The once marked in a red box are the downstream sensor after the TWC, these are the sensors that monitor the function of the TWC, if they are functioning below the given set monitor specs, then the code will trip to let you know if the TWC are not working correctly .
If the sensors are good and there is no exhaust leak and you don't have any misfire codes or any other codes, then the chance that the TWC is bad is very likely.

The cost of the sensors very from dealer to dealer , you can get original Denso sensors at Rockauto.com at a very good low price .

My goal is to provide you with excellent service – if you feel you have gotten anything less, please reply back with the reply box below and not the poor or bad service button ,

For further assistance there is no extra charge after accepting.

Rgds Greg
Customer: replied 1 year ago.

Hi Greg


You asked for the code in order to reply. Your reply is basically "take it to a repair shop".


What is the significance of code PO420. You refer to numerous sensors such as MAF, crank, IAT etc. That is why I asked how many there are. If the code refers to bank 1 does that indicate that the problem is in that converter or one of two sensors.


As an expert shouldn't you know the cost of a sensor? Is an A/F the same as an o2?


Am I a pain?


 

Expert:  Greg replied 1 year ago.
Hi Frank .

No your not a pain Wink LOL.

Okay the Cat is most likely the problem if you have no other codes, and all the other sensors are working as they should ,these only have to be checked when the system is being checked with the scan tool, this is done with the live date mode a quick check .

I just like to be sure before replacing an expensive part .

The P0420 refers to the cat not working to full expectations according to the downstream O2 sensor (After the cat) Now if this sensor is working correctly then the cat needs replacing .

Need any follow up answer no problem Frank, even after accepting my answer i will stay with you until you are happy and have your car running as it should ..

Kind regards Greg
Greg, Import tech
Category: Lexus
Satisfied Customers: 5732
Experience: 17 year shop owner
Greg and other Lexus Specialists are ready to help you
Customer: replied 1 year ago.

Greg

I did give you a rating.

Thanks.

The problem was a sensor and an exhaust leak near the sensor.

Frank

Expert:  Greg replied 1 year ago.
Hi Frank .

Thanks Frank.Good you got it sorted out ,all the best my friend .

Rgds Greg

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