99 lexus GS-400 P420, where is the O2 sensor? Need Pics not words

Got it scanned and it's P0420: Catalyst efficiency below thresholdbank 1. They said it could be a bad catalytic converter or oxygen sensor. I borrowed a scanner and tried to measure the oxygen sensor readings over time.Sep 8, 2011


civic - Check Engine code P0420 Catalyst efficiency below ...

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P0420 Error Code: Catalyst System Efficiency Below ...

www.obd-codes.com/p0420
P0420 OBD-II Trouble Code. Technical Description. Catalyst System Efficiency Below Threshold (Bank 1). What does that mean? This diagnostic trouble code ...

P0420 Code Fix How Its Done Catalyst Efficiency Below ...

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Here is a tutorial on P0420 code fix catalyst efficiency below threshold How To Diagnose a p0420 code ...

Catalyst System Efficiency Below Threshold (Bank 1). OK, now tell me that again in plain English please.... let's break it down: the catalyst system being referred to is your three-way catalytic converter; so the catalytic converter is not working properly (i.e. it's not efficient). Bank 1 refers to the side of the engine which contains cylinder #1. On inline engines such as 4 & 5 cylinder engines, there is only one bank. So, to really simply things let's just say that the efficiency of the catalytic converter and/or exhaust pipe and/or O2 sensor is not so great. Hope this helps.

The P0420 means Catalyst System Efficiency Below Threshold (Bank 1), and the P0430 means Catalyst System Efficiency Below Threshold (Bank 2).
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P0420 - Catalyst System Efficiency Below Threshold Bank 1http://engine-codes.com/p0420.htmlForum CodePossible 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
- Engine Control Module (ECM) Tech notes The most common cause it the three way catalyst converter Bank 1. Changing just the O2 sensor usually don't repair the problem. If the P0420 code is combined with other codes, try fixing the other codes first.

P0420 = Bank 1 catalyst system efficiency below threshold. This DTC (Diagnostic Trouble Code) is set when the O2 downstream sensor indicates/measures the amount of hydrocarbons/oxygen present in the exhaust after it passes through the converter. When this sensor detects exhaust gasses identical/near identical to the upstream O2 Sensor (the actual gasses at the exhaust port - before the converter), it will set this 'efficiency below threshold' code. The catalyst has failed to 'convert' the exhaust gasses to CO2 + Water.

ok lets do this in order
P0420 Catalyst System Efficiency Below Threshold (Bank 1) an o2 sensor bad usually before the Cat converter P0430 Catalyst System Efficiency Below Threshold (Bank 2) same thing but the sensor after the cat converter the c1734 people will say you need to replace a bad BCM, but don't,, once the O2 sensor problem is addressed , that code will clear , it has to do with the remote start b2090 has to do with power doors ,, this will drop off too once the system is rest , same with the last one you listed, If I was you I'd have the 2 O2 sensors checked, replace the bad one, or both, and have the mechanic clear all the codes, then recheck them

Hi and welcome to FixYa!

Code p0420 means Catalyst System Efficiency Below Threshold (Bank 1). This will surely needs attention to resolve the problem.

Hope this helps and thank you for using FixYa! Have a good one!

P0420 is catalyst below threshold. It is triggered via the rear o2 sensor (post cat), so you may want to check that sensor to make sure it's functioning properly.

P0420 Error Code: Catalyst System Efficiency Below Threshold (Bank 1) Repair information for the OBD-II trouble code P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
www.obd-codes.com/p0420

p1460 cooling fan circuit,p1153 ho2s insufficient switching bank 2 sensor 1,p1133 insuf. swit. sen. 1 or bank 1 sen. 1,p420 catalyst system efficiency below threshold bank 1,p152 o2sen. circuit high volt. bank 2 sen.1