In my last post, I described the problem with my 2002 Honda CRV. The Check Engine Light (CEL) came on, and the mechanic wanted mucho dinero to fix it. His estimate was almost half of the car’s trade-in value. I decided to buy an OBD-II code reader and do a bit of investigation myself. Here, then, is the rest of the story…
The diagnosis
The scanner found three codes on the CRV: P0430, P1166, and P1167.
My secret decoder ring tells me that the “P” means powertrain. The first number is either a “0″ or a “1″. Zero means it is a generic problem, and a one means it is specific to the model. My reader was no help in the Honda-specific codes, directing me to a telephone number.
I went, instead, to the web. There are several sites to help you understand the codes. I found obd-codes.com to be the most helpful. Or google “2002 Honda CRV P1166″ and you’ll find not only the problem code, but descriptions of how to repair it, and trouble spots that other DIY’ers found (and how to avoid them). By then end of a dozen clicks, I knew more about automotive emission systems than I ever though I would need to.
The P0430 code, indeed, pointed to replacing the catalytic converter, but that code (when erased) cleared and has not reappeared.
The other codes, P1166 and P1167, are both related to the oxygen sensor. This is a $150 part and it just screws into the inlet portion of the catalytic converter; hence, it requires virtually no labor. I could see my repair bill drop from $2,200 to about $300. Whew!
The key failure: Oxygen sensor
The oxygen sensor is used to measure the amount of oxygen in the exhaust. That information is fed back into the fuel injection system to determine the optimal amount of fuel and air to let in for every combustion cycle. If it’s not optimized, your gas mileage drops.
An oxygen sensor uses an oxide semiconductor (alumina, zirconia, zinc oxide,…). The oxygen ions move through the lattice carrying charge, creating an electrical current. The number of oxygen ions is proportional to the partial pressure of oxygen at the surface. Oxygen ions are really slow, so to improve the response of the sensor, they heat it up. It is the heater on the oxygen sensor that fails. This is a fairly common item to replace.
Gettin’ dirty
Just for kicks, I crawled under the car to see if I could figure out where it goes. It was a cinch to follow the exhaust pipe back to the catalytic converter. There are two thingys going into the catalytic converter. I was pretty sure it was the one on the left, since it didn’t look like original equipment, and I have had the sensor replaced before.
It looked really easy to replace. Just unplug the sensor and unscrew it. How hard could that be?
So I read some more online, and found one guy who pushed so hard on the wrench trying to get the sensor out, that he broke the wrench. Yikes! I would think if you put that much force on it, you could break the cat converter, and then I’m back to looking at a $2,200 repair — if not more.
Dealing with the repair shop
So I decided to take it to the shop. I had it replaced in about 30 minutes, but they charged me $420. Ouch! Still, better than the $2,200. But I think I might start shopping around for a new repair place.
There are two kinds of repair guys. I can imagine there are repair guys out there who would love to work with a customer who took the trouble to investigate the problem herself — like the Car Talk guys. Then there are the guys who feel threatened by that same customer — like, unfortunately, my current shop.
I’ve decided that there’s a difference between service and repair. I trust these guys to change the oil and to put on new brake pads, but I think I’ll be doing more of the diagnosing myself in the future.
How to become the most popular person in the office
I can reset engine lights. I am powerful. I am sexy. Hear me roar.
So far I’ve “fixed” cars for two colleagues. They are forever in my debt. This is always a useful thing.
Although my experience with fixing cars is extremely limited, what I’ve seen so far is that most CEL’s are caused by one-time-only problems. Reset the engine light, and it doesn’t come back on. Why I should take my car to the mechanic?
An OBD-II code reader may just be the best investment I’ve ever made.
Related Posts: How to Reset Your “Check Engine Light”: OBD-II Code Readers
Disclaimer: No position in any company mentioned in this post.
Image credits: All photos are my own.
Science and Money Feed
Nicolas
on Jan 8th, 2010
@ 8:44 pm:
As I always buy used vehicle, I must say that this is an amazing idea.
You are clearly my hero of the week.
Helen
on Jan 9th, 2010
@ 12:33 am:
Why, thank you, Nicolas. How nice of you to say that!
Howard
on Jan 21st, 2010
@ 6:12 pm:
Helen,
I am glad you did some investigating about your problem, although It looks like the picture of your exhaust you have two oxegen sensors one is probably heated and the other is regular. You can easily take these off with a oxegen sensor wrench, which sometimes you can rent from parts stores, maybe even free. Also a little dab of a penetrating type oil to loosen can help. As far as engine lights as we drive our cars the computer checks various monitor’s under different loads city and highway. Some monitors only test themselves at certain times. I hope that 420.00 repair included the sensor because that was quite high.
Helen
on Jan 25th, 2010
@ 10:26 pm:
Hi Howard,
I was wondering about the fact that there do seem to be two oxygen sensors. I checked out a Haynes Repair Manual (for Honda CRV’s) from my local library, and it only shows one sensor in the catalytic converter. (So why, indeed, do I see two?) The $420 did include the sensor, but it still seemed like a lot of money. I was tempted to repair it myself, but afraid of braking a corroded part — maybe I should have been braver. Maybe next time. Thanks for writing in.