juror

Hello. Leaving Memorial Day celebrations yesterday, the MIL came on in my partner's 2005 Civic EX.

We swung by an AutoZone and had them hook up an OBD-II scanner to make sure it wasn't code "P0666 Engine Possessed" or something that could cause serious damage to the car or engine over the course of our ~100 mile drive home. Got a "P0134 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)". And so we drove home without incident.

Since I haven't been the one dealing with the maintenance of the car and since my partner might be best described as indifferent when it comes to cars, I started with some searching and learned the following:

1) It's not an O2 sensor, it's a Linear Air/Fuel (LAF) sensor. Source: various threads here, including this plum.
2) Denso makes the OEM part. Source: Various threads here.
3) A VIN search on Denso's website turns up 3 different sensors for each of the D17A1, D17A2, and D17A6 engines. Source: Denso
4) A US-spec EX (which this is) has a D17A2 in it. Source: Wikipedia
5) Items 3 and 4 indicate that I need Denso Part #234-9017, which is corroborated by this thread.

I've done a little bit of looking around for this part, and found a couple options:

1) Majestic for $250
2) RockAuto for $140
3) Amazon for
At this point I have a couple of questions:

1) Any obvious screw-ups in my thought process getting to that part number? It seems reasonable to me, but I'm not an expert.

2) Has anybody had luck getting auto parts from Amazon? I'm looking for confirmation of basic stuff like "The part matched the description and had the correct part number".

3) Where is the part number on these things to confirm receiving the right one? Obviously I have one on the car, but I'm not pulling it for a close look until I have a replacement.

4) How bad are these to change? It looks like I can get a correct wrench in from the bottom, but my limited experience messing with exhaust stuff is that everything is seized (Yes, I'll put anti-seize on the new one). Do I risk ripping the boss out of the pipe it's mounted in, for instance?

Thanks!

Lokin4Areason

heck, I would like to know to this ( also have a 05 ex )

Reverb2005

Sounds like you did some research, good job!

1) Did everything we would have told you here on the forum, except for actually checking the physical sensor.

Be sure the sensor is plugged in tightly at the connector and that the contacts are not corroded. Do you know where to find the A/F sensor in your vehicle?

2) I purchased my OXYGEN sensor off Amazon, no problems, it was Denso and the exact part number I was looking for. These sensors are marked up like crazy at the dealership and other places, Amazon is the way to go!

3) It may be really hard to find the part number, but you should be able to see the manufacturer logo on the sensor itself. It may be really rusted but if you clean it up with some fine grit sandaper or a wire brush you will see it. I think Honda uses NTK from the factory but lots of people have used Denso with no problems. DO NOT GET BOSCH!

To see exactly what engine you have, there is a sticker on the timing belt cover, take a look to be exactly sure.

4) For me, changing the O2 sensor was not hard at all believe it or not. I thought it would be seized up too but looks like the factor put some anti-seize on. If you get the Denso sensor, it actually comes with a little tube of anti-seize!

You will need the proper socket though, the one that allows you to put the signal wire through the socket and still get the nut off.


That's the oxygen sensor socket, though it may work for the A/F sensor too, if it is the exact same size nut... check that out before buying.

It really isn't a difficult DIY if you are ok with a wrench... that's pretty much it.

juror

Thanks for the helpful reply. To answer some of your questions:

My understanding is that there are two sensors in the exhaust system:
1) The LAF sensor (B1S1) upstream of the catalytic converter
2) The O2 sensor (B1S2) downstream of the catalytic converter

P0134 is for the LAF sensor. With that in mind, I popped the hood and started following the exhaust system from the engine. The LAF sensor appears to be the doodad sticking out of the exhaust system on the pipe running from the manifold to a 90 degree elbow that turns the exhaust from flowing downwards to rearwards.

I confirmed that there's another doodad with wires attached farther downstream, so I'm fairly confident I'm looking at the LAF between the block and the radiator.

The wiring appears to be in good shape. I haven't disconnected the connector that attaches the sensor to the wiring harness to check for dirt or corrosion, but I can do that later tonight and confirm the engine in the car.

I couldn't find a pinout for the ECU. If I could, I suppose I could verify the connection back to it (I own a cheap DMM), but I'm reluctant to start pulling out those giant plugs in a tight space without having a pretty clear plan in mind.

Reverb2005

Yes, you are correct, you will see the A/F sensor upstream of the CAT. You should see your CAT attached to the exhaust pipe under the engine and, as you said, it is the sensor closer to the engine, farther from the muffler.

Heck, here we go, #19




Good luck and let us know how it goes.

juror

I've confirmed that the contacts are clean. I hit 'em with DeOxit anyway for good measure. No luck on that.

Thanks for confirming that you had a good Amazon experience. It looks like I'm in for a hundred and some bucks there in the near future. :-)