COAL Update: You’re Gonna Wanna Check That Out

My daughter is home from college for the holidays. She and a friend set out in the driving rain for a town two hours away in Bertha, and Bertha let them know she wasn’t too pleased with that.

Actually, Bertha (our 2007 Mercedes S550) ran just fine, but the check engine light came on and stayed on. My daughter called me from the road, but I told her if it was running OK, then it should be fine to keep going.

The next day, I started the car and the light stayed on. So, I got out my trusty Bosch code reader and took some pictures to share with you all.

Many of you I am sure have such a reader, but if you don’t they are well worth the price. They have come down in cost significantly. This one was about $70 on eBay, new in the box. It is a universal type, so it reads the basic codes that are universal to all cars built after 1996.

If it recognizes your car, it will read additional codes specific to that make and model. It recognized Bertha, here.

It first looks for codes. I would assume the check engine light would not come on without a code, but it’s also possible the light would eventually reset with a code still being “stored” in the system.

Using the keys on the reader, we highlight the code and ask to read it out. I don’t recall getting this code before. Google tells me that “PO432” can be caused by many things, but most likely is a failing catalytic converter that results in the converter not working as well as it should. With 11 years and 204,000 miles under her belt, Bertha’s converters may well be checking out on us.

If there was a second code for an oxygen sensor, then that would be the likely culprit. But without an oxygen sensor code, there’s probably no reason to start throwing parts at her.

I also wasn’t too concerned as she just passed the State emissions test the weekend prior to the check engine light coming on. I doubt there has been some catastrophic failure of the catalyst since last Saturday. It may not be working perfectly, but it’s apparently working well enough to pass emissions.

Our tag renewal sticker has already been issued, so we are legal until Jan. 15, 2019 regardless.

I reset the light, and it has stayed off since.

After this screen, I usually unplug it. I continued to play around with the reader, which I haven’t really done before.

This is apparently what the State emissions computer sees when it is plugged into your car, as this same information is printed on the paper inspection receipt you get.

Freeze frame data is all the information about what is going on in the vehicle’s monitored systems, when an emissions fault occurs. It is stored when the fault occurs for two consecutive trips. Either it didn’t occur twice here, or, I erased the freeze frame data when I cleared the code.

There’s quite a menu of things you can do and read. This is just one of several screens.

All kinds of information is monitored and stored by the car. It’s amazing to me all these sensors and computers even work reliably after 11 years, given the harsh environment of a motor vehicle.

Even something as simple as the gas gauge is involved!

I guess the “gauge” is really nothing more than an analog readout of the computer data, for us dumb humans.