10% Ethanol = 100% Headache?

I recently had an engine warning light come on. I was told it was Oxygen Sensor One. Oxygen Sensor One was replaced. Then within the week another warning light. Cause: Oxygen Sensor Two. Oxygen Sensor Two was replaced. Before I could get home from that repair, the warning light came on again! I drove straight back to the shop. This time the mechanic’s code said it was the Catalytic Converter. Before this recent string of problems, I had already replaced both oxygen sensors and the catalytic converter once before. (I bought this car four years ago.) One of the service managers told me they are attributing these kinds of problems to the mixing of ethanol into gasoline. Is there any truth to this? Should I be looking for ethanol-free gas from now on to avoid further problems? Ironically, my other car is 1998 Plymouth Grand Voyager which was one of the first

flex-fuel vehicles made, and it runs great on E-85.

I neglected to mention the car in question is 2003 Honda Civic Hybrid

Your 2003 Honda engine is designed to handle E10 gasoline. So I doubt that’s where the problem is.

If O2 sensors are being taken out one after another, I’d start looking for some sort of contamination in the exhaust stream. Like maybe coolant?


A cold chill went down my spine as read your comment. If coolant is getting into the exhaust system, how is it getting in there? Could this possibly mean a cracked engine block? Or could it be something more benign?

What have the actual codes been and how exactly has this shop been deciding that you need O2 sensors? FYI: there is no computer code that can tell you that an O2 sensor is bad, and O2 sensors are one of the most common whipping boys for various codes. It sounds to me like these characters are guessing and throwing parts rather than doing diagnosis.

So find out what your actual code(s) is/are and report those. They look like “P1234”

Oh - and the ethanol thing is bogus. Maybe you need a new shop.

It never ceases to amaze me how much money gets spent on cars that run PERFECTLY but have a pesky little nag light glowing…

I believe that the “check engine light” should be renamed the “check emissions light”.

Click and Clack’s suggested fix for many codes is a small piece of black electrical tape over the light.

Very true, but then ignoring a light can cause expensive damage that could have been prevented by a minor repair.

Actually, I’ve been dealing two different shops. The first is a Honda service department (we’ll call them Mechanic “A”) which I have gone to for years. They were the one’s who made the comment about the ethanol-gas. They didn’t directly imply the ethanol was responsible for the problems. They simply said they have seen “a lot more of my kind of problems since the ethanol-gas was introduced.” They replaced the first oxygen sensor.

The second place is a private shop run my a former Honda mechanic (we’ll call him Mechanic “B”), who broke from a different Honda dealership than the one just mentioned above years ago, because he didn’t approve of the way they were charging customers to make unneeded repairs. He has a good reputation, but by his own admission he says he is not very familiar with hybrid cars. He showed me the code on his scanner, which was like you said P-something. He said he can only go by what the scanner tells him, as there is apparently no other way to know what’s wrong.

This car has had some other issues of late. On my way home from my last visit with Mechanic B, I stopped at Advance Auto Parts to get some oil/filter to change the oil on my 1998 Plymouth Grand Voyager. While there I asked them to plug their scanner into the Honda. They, too, came up with Oxygen 2 Sensor, AND “fuel mixture too lean.” I have had problems with my hybrid getting poor gas mileage lately. And on two occasions when I attempted to start the car, it would stall within seconds of starting, even on several repeated attempts. Mechanic B said it could be the fuel relay system, which could act up on hot days (both occurrences happened on hot days).