Cel And Trac Lights

[camlex]

Hello,

Yesterday CEL and TRAC both light came on, due to sunday, I continue driving. fill up some Chevron Gas.

This morning turn car on to go to Autozone to check codes. No more lights.

Any ideas?

Thanks in advance.

[George_Jetson]

Sounds strange, I am very surprised that there would be no stored codes. It might possibly be a quirk of the model code reader that Autozone used. It probably is not anything to be too concerned about, but if you are really curious you could purchase a recorder. Recorders plug into the OBDII port and records the data stream, depending on the amount of memory, the storage can cover a long period of driving. Professional scanners have had this function for a long time. I have just found out about the hobby version a short time ago. You can pick them up for around $60, and there is a interface that plugs into you PC compatible computer.

[camlex]

Thank you.

I went oreilly and requested to check memory code. His answer was without CEL He can't check. after 2nd request he connected and shows P0420 Bank 1. I don't think Cat goes bad this early at 138,000. Well, Presently no light and i am going put so many miles tomorrow, see what happens. usally CEL light come back 50-100 miles correct?

Again, Thank you.

[George_Jetson]

You are welcome, glad I could help you in the past.

I suspected that there was a stored code. I am not too surprised that the guy at oreilly was mistaken, a lot of people do not understand how it is suppose to work, and I feel that some of the basic scanners are a little misleading, and only add to the confussion.

You are correct that P0420 is for the cat efficiency but the cat is not the only problem that could set the code. To explain the basic operation of the system, The upstream O2 sensors are used to controll the fuel to air mixture. The Ecm varies the mixture from rich, to lean, trying to keep the upstream sensors switching continuously. The downstream O2 sensors are located after the cat, and they also monitor the switching from rich to lean. The cat uses the excess O2 to complete combustion of the exhaust gases so as a result the downstream sensor will switch at a slower rate than the upstream.

With this in mind, the you first need to check the upstream sensors, and the exhaust system for leaks, and next the downstream sensor. Have the O2 sensors been replaced? They recommend replacing them around 80k, so they would be the first suspect.

[George_Jetson]

You are welcome, glad I could help you in the past.

I suspected that there was a stored code. I am not too surprised that the guy at oreilly was mistaken, a lot of people do not understand how it is suppose to work, and I feel that some of the basic scanners are a little misleading, and only add to the confussion.

You are correct that P0420 is for the cat efficiency but the cat is not the only problem that could set the code. To explain the basic operation of the system, The upstream O2 sensors are used to controll the fuel to air mixture. The Ecm varies the mixture from rich, to lean, trying to keep the upstream sensors switching continuously. The downstream O2 sensors are located after the cat, and they also monitor the switching from rich to lean. The cat uses the excess O2 to complete combustion of the exhaust gases so as a result the downstream sensor will switch at a slower rate than the upstream.

With this in mind, the you first need to check the upstream sensors, and the exhaust system for leaks, and next the downstream sensor. Have the O2 sensors been replaced? They recommend replacing them around 80k, so they would be the first suspect.

[George_Jetson]

.

[George_Jetson]

You are welcome, glad I could help you in the past.

I suspected that there was a stored code. I am not too surprised that the guy at oreilly was mistaken, a lot of people do not understand how it is suppose to work, and I feel that some of the basic scanners are a little misleading, and only add to the confussion.

You are correct that P0420 is for the cat efficiency but the cat is not the only problem that could set the code. To explain the basic operation of the system, The upstream O2 sensors are used to controll the fuel to air mixture. The Ecm varies the mixture from rich, to lean, trying to keep the upstream sensors switching continuously. The downstream O2 sensors are located after the cat, and they also monitor the switching from rich to lean. The cat uses the excess O2 to complete combustion of the exhaust gases so as a result the downstream sensor will switch at a slower rate than the upstream.

With this in mind, the you first need to check the upstream sensors, and the exhaust system for leaks, and next the downstream sensor. Have the O2 sensors been replaced? They recommend replacing them around 80k, so they would be the first suspect.

[George_Jetson]

You are welcome, glad I could help you in the past.

I suspected that there was a stored code. I am not too surprised that the guy at oreilly was mistaken, a lot of people do not understand how it is suppose to work, and I feel that some of the basic scanners are a little misleading, and only add to the confussion.

You are correct that P0420 is for the cat efficiency but the cat is not the only problem that could set the code. To explain the basic operation of the system, The upstream O2 sensors are used to controll the fuel to air mixture. The Ecm varies the mixture from rich, to lean, trying to keep the upstream sensors switching continuously. The downstream O2 sensors are located after the cat, and they also monitor the switching from rich to lean. The cat uses the excess O2 to complete combustion of the exhaust gases so as a result the downstream sensor will switch at a slower rate than the upstream.

With this in mind, the you first need to check the upstream sensors, and the exhaust system for leaks, and next the downstream sensor. Have the O2 sensors been replaced? They recommend replacing them around 80k, so they would be the first suspect.

[camlex]

CEL and TRAC lights came back after 200 miles and Code is P0420

O2 sensors or CAT.?

Thanks,

[George_Jetson]

In order to tell exactly what is going on, you are going to need a scanner. First you need to check the upstream sensors, the exhaust system for leaks, and then the downstream sensor. Have the O2 sensors been replaced? They recommend replacing them around 80k, so they would be a strong possibility. A scanner is necessary to figure out exactly what is going on.

[camlex]

Update:

Since daughter taking car to austin, I don't want any phonecalls from her.

P0420 was the code. Local shop replaced Cat with CATCO cat. total cost was $200. Model#608216

Thank you for your inputs.

[George_Jetson]

Please do me a favor and keep me send me a update in the next couple months.

Thanks

[camlex]

you think light will come back?

[George_Jetson]

I would hope not, but it is possible. I have never had the opportunity work on this code. I would find it very interesting to put a scope on both sensors at the same time.

[camlex]

Last month, my sienna had P0135 CEL code at 157,000 and i did replaced both O2 sensors.