Learn how to handle a 2000 Chevy Tahoe with P0161 DTC, & what to do when a 1998 Cadillac Catera's brake lights won't turn off, in Vincent Ciulla's latest repair article.

This weekly Q&A session answers your questions about cars and trucks. This week explores a 2000 Chevy Tahoe with a P0161 DTC and a 1998 Cadillac Catera with brake lights that won't turn off.

Question: 2000 Chevy Tahoe Limited

Hi Vincent!! How are you doing? I have a 2000 Chevy Tahoe Limited, it's the 1999 body-style and has the Vortec 5.7 liter V-8 it's a 2WD with A/C. I've recently had a "Service Engine Soon" light pop on at 172,000 miles. I hooked up a code reader to it and it told me the error was "P0161 B" O2 sensor heater bank and also told me it was 02 sensor 1 bank 2. I just wanted to know if this is correct and which side that sensor would be on. I know I have 4 sensors total; one before each cat and then one after each one. The dealer changed the sensors at 100,000 miles but I'd really like to save some cash this time.

Thanks for your time and help,

Marco

Answer:

DTC P0161 is "Heated Oxygen Sensor (HO2S) Heater Circuit Bank 2 Sensor 2". What this code is saying is that there is a problem somewhere in the HO2S heater circuit. The problem is not necessarily a bad HO2S, but in the circuit itself, which does include the HO2S. Chances are good it is a bad HO2S but you check the whole circuit before replacing the HO2S.

That vehicle had two different exhaust systems installed in it depending in the equipment package. Check the diagrams of both systems to determine the locations of your HO2S.

Question: 1998 Cadillac Catera

Help! My father recently gave me a 1998 Cadillac Catera that was my mother's before she passed away in 2000. It has a lot of sentimental value to me, but I am not sure if it is worth any problems that I may have beginning now. During the day the brake lights work fine when daytime running lights are on, but when the lights are on at night the brake lights come on and stay on also, so it appears as if I don't have any brake lights. Any suggestions? I did recently change the left rear brake light bulb. I have already checked all of the fuses and they are all fine.

Cindy

Answer:

When this happens, it is usually the result of having the wrong type of bulb installed in the lighting sockets. Remove all the tail light bulbs, one at a time, and check them for the right type. Parking and tail lights use single filament bulbs and brake and turn signal lights use a double filament bulb. If a single filament bulb is installed in a double filament socket it will bridge both socket contacts causing the brake lights to come on with the headlights.

If you find that all the bulbs are correct you may still have a bad dual filament bulb. Replacing them, one at a time will reveal if this is so. If not then you probably have a short in the wiring.

That’s all for this week. Feel free to browse the archives for past topics. And, as always, if you are stuck and need an immediate answer you can always call Vince on the phone.

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