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What kind of cat????
Is it factory????
Aftermarkets cats that are cheap do not have enough precious metals in them and they fail at about the time you describe.
I first two were replaced by the subaru dealership so I ahev to assume they were factory. The third was done by my mechanica. He ssays I haev 3 converters in my car. He replaced one with n upgraded model which is now used on Subaru outbacks because fialure of the catalytic converters is quite ocmon in this car but this time the code keeps comming back on but when checked ist says the converts are fine and it passess the emmission tes?
what are the codes??? 420 and 430 are cat efficiency codes. they are definitely no good if they are the codes.
You do have 3 cats but the primary cats are the 2 in the front. the rear cat is a secondary cat that picks up the remainders of the fronts.
Does the engine run ok?? if it runs rich or with a miss it will destroy the cats from excess fuel dumped into the converter.
There are no codes just the lights comming on. When the mechanic reads the diagnostic the codes say everything is fine but the check engine light and the cruis control lights keep comming on. The engine seems to be running a little rough in idle and is slugish going up inclines. The spark plugs were replaced 4 months ago.
if the light is on there is codes. codes never say that everything is fine. it tells you the area of a failure that needs to be checked.
the rough idle and sluggish could be your real issue. I would start with a compression test to verify the motor is in good shape. the wires and coil need to be checked as well as the injectors.
Still need the codes
There are no codes. When the mechanic checks the diagnotic does not show codes so essentially the computer is saying nothing is wrong even though the check engine light is on.
ok, there is an issue with the control systems as the light is on for a reason. Maybe it is the scan tool the tech is using but there should be some information that he can read about the O2 sensors and if they are reacting correctly for the cats. Just because there are no codes does not mean that ever thing is fine. You have 2 issues here with failing converters and a check engine light storing no codes. I will put this out to the other guys who may have better ideas on this.
Ok. The O2 sensors have been checked and they are working. I have have the codes checked by two different mechanics each time the check engine light comes back one and each time there has been no code. The check engine light does cycle. It comes on after 1/4 of tank of a full tank is used goes off at a half a tank, comes back on at the final 1/4 of tank.
Hello and welcome to JustAnswer!
If the check engine light is coming on yet no fault codes are setting then the problem has to be in the engine controller or the instrument cluster. The reason the check engine light comes on is because fault code sets and the light alerts the driver. If the light is truly coming on with no codes set then either the ECM is sending a MIL request when there are no codes set and it will need to be replaced, or the cluster is turning the light on for no reason because it has internally failed.