kak41

Sorry this is going to be so long, but I’ve searched these forums and googled my problem, but I’m not satisfied with what I’ve been finding. Excuse my ignorance. I know nothing about cars, but I’d like to learn.

I have a 2001 Honda Accord EX coupe, 4 cylinder with 135,000 miles. No previous problems, except I had the transmission replaced in 2008 at 95,000 miles (it was under a recall).

The CEL has been coming on intermittently for the past 4 weeks. I’ve noticed that it comes on during city driving, but it goes off (almost immediately) when I drive long distances on the highway. Also, sometimes when it’s idling, it sounds/feels like the engine shudders. I took it to AutoZone, and got the following code: P0135 A/F sensor 1 heater system malfunction. Probable causes are open/short circuit condition, poor electrical connection, or faulty A/F sensor 1.

First question: About 4 weeks ago when this problem began, I cleaned my K&N air filter. I turned the car on, and the check engine light came on. I immediately (literally 15 seconds later) turned the car off and replaced the filter with a regular filter from AutoZone. When I looked over the K&N filter, it was dripping with excess oil. If the filter was overly saturated, could this have caused my problem? I kind of don’t think it would, simply because the problem is intermittent but ongoing, and I’ve since removed that filter. Is this just coincidental?

Second question: The fact that the light goes off during highway driving and on in the city, does this mean the problem is more than likely the A/F sensor, and not electrical or a short circuit?

Third question: If it’s the A/F sensor (same as O2 sensor, correct?) could I replace the part myself? I’ve called dealerships, and I’ve been quoted what seem to be outrageous prices ($450-600!).

Thanks for your help!!

freefall365

your air filter was dripping with oil?

kak41

It's a K&N reusable air filter. I cleaned it with the K&N cleaner, then I sprayed the K&N oil. I either sprayed too much, or didn't give it enough time to set.

MAD_MIKE

It could be that the oil from the K&N filter was able to make it through the combustion process and did contaminate or poison the O2 sensor. It also could be a coincidence that the heater circuit of the O2 has failed. Did you inadvertently drop anything near the exhaust manifold, possibly hitting the O2 sensor?

Simple solution would be to just replace the O2 sensor.
Use a Denso, Delco/Delphi or NTK brand. Other brands are badly or cheaply made and will not work correctly.
Rock Auto sells the Denso unit for $56.79. And the discount code RockAuto 5% off 40706053351777 expires November 28, 2010

redbull-1

See this thread just to make sure whether your engine is a F23A1 or F23A4. See post # 17.

https://honda-tech.com/forums/showth...=oxygen+sensor

The F23A1 engine uses an oxygen sensor (narrow band), while the F23A4 engine uses an Air/Fuel Ratio sensor (wide band). The A/F ratio sensor is more expensive.

Usually, P0135 is an oxygen sensor code though instead of the A/F sensor; but, check the engine version just to make sure. The sensor is located in the front (it is seen near the bottom of the image in that thread, below the hand with the X over it on the exhaust manifold cover) and can be taken off with a 22mm or 7/8" oxygen sensor socket, or wrench if you remove the exhaust manifold cover. You could always go to an independent mechanic to get it replaced for far cheaper than what you are being quoted by the dealerships.

I very much doubt the excess oil from the K & N filter would cause the check engine light to come up right after you put in the K & N filter and turn the car on.

Wrenchin24-7

Wow Thanks man. I need a new o2 sensor on my cb7 and i was just gonna use a duralast. but for the same price i'm gonna go ahead and throw in the denco/delphi. Appreciate the heads up

jdowen2

If you over oil a K&N in a Chevy you foul the air flow sensor. Might want to check that also.

redbull-1

A 2001 Accord doesn't have a mass air flow sensor.

joe_accord23

could be a contiminated 02 sensor, and yes u need to replace it.