Question

What are the engine codes P0420 and P0430 on my 2004 Toyota Highlander 3.3L V6?

Answer 1

Discription

Indicates the bank 2 catalyst system efficiency is below the acceptable threshold

Possible causes
 

Use of leaded fuel

Damaged heated oxygen sensor (HO2S

Out of range engine coolant temperature (ECT) sensor

High fuel pressure

Damaged exhaust manifold

Damaged catalytic converter

Oil contamination

Cylinder misfiring

Downstream HO2S wires incorrectly connected

Damaged exhaust system pipe

Damaged muffler/tailpipe assembly

Retarded spark timing
leaking fuel injector

Diagnostic Aids

 

The signal line lengths of the downstream HO2Ss are compared against the signal line lengths

of the upstream HO2Ss. Under normal closed loop fuel conditions, high efficiency catalysts have

oxygen storage which reduces the frequency and amplitude of the downstream HO2S as

compared with an upstream HO2S signal. As catalyst efficiency deteriorates, its ability to store

oxygen declines and the downstream HO2S signal has an increased amplitude and frequency,

approaching the amplitude and frequency of the upstream HO2S. Once beyond an acceptable

limit the DTC is set..

Comments

Vehicles with universal HO2Ss compare the signal line length of the downstream HO2Ss to an
expected signal line length of the downstream HO2Ss with a deteriorated catalytic converter.

Answer 2

This code is for the bank #2 catalytic converter. Typically to repair this code the converter must be replaced.On occasion a rear O2 sensoron bank 2 can also cause this code to come up.

Answer 3

P0420 2004 TOYOTA HIGHLANDER - Catalyst System Efficiency Below Threshold Bank 1
Read more: https://www.autocodes.com/p0420_2004_toyota_highlander.html

P0430 2004 TOYOTA HIGHLANDER - Catalyst System Efficiency Below Threshold Bank 2
Read more: https://www.autocodes.com/p0430_2004_toyota_highlander.html