Hello all,

I've been taking a vested interest in tinkering with Hondas as of recently, so I have volunteered my services to help out my friends and family members with any repair jobs that they may need to perform on their cars.

With that said, I spent yesterday (well..only an hour or so really ) helping my friend change the two o2 sensors on his '03 Pilot. This is a pretty elementary job but I figured that I'd share a quick walk-through on the procedure

Note to DIYers: An O2 sensor wrench (SP Tools 93750, or equivalent) is commercially available for removal and installation of this component. My friend already had one but if you don't own this wrench then you can pick it up at any good auto store.

1) Disconnect the HO2S 4-pin connector (A), then remove the HO2S (B).

2) Install the HO2S in the reverse order of removal.

3) Tighten the sensor to 33 ft. lbs. (44 Nm).


**Shown here: Removing the primary HO2S—2003–2004 models**


**Removing the secondary HO2S—2003–2004 models**

--Additional Reference diagrams--

2003 Pilot exhaust diagram <--shows the entire exhaust system, providing a nice frame of reference

 

I have to reply to this post. I don't mean to offend stock00 but I can't think of any other way to put this except to say that your instructions are all but useless. In fact, I find it hard to believe that you actually replaced an O2 sensor on a Pilot. You simply copied the instructions from the service manual word for word and scanned the illustrations but anyone who has actually done this job knows that the manual left out some very important information in this case. (I have the manual.) Your post reminds me of an old comedy routine that used to be on Saturday Night Live or a radio show decades ago (I can't remember which). In that regular skit, an "answer man" would be asked a question like, "How do I become a brain surgeon? " His answer would be something like, "1) Get a medical degree. 2) Open a practice."

The instructions you copied from the manual simply tell you the goal of the job, not how to do it. The service manual is good for many things but it's terrible in this instance. It's the "how to" that is needed. For example, you (the manual) make no mention of how to locate the front connector. When you find it, it's extremely difficult to get at. If you have big hands like mine, good luck! When you do, you may find that the connector simply won't release when you press the little lever. The manual also doesn't mention that you must remove it from a bracket clip to remove the sensor and cable and, to do that, you will almost certainly have to remove the bracket itself - all in a very tight location. It can also be a real problem to even get it off the bracket. It can be a real pain, to put it mildly. This is not just a matter of the steps you copied. Anyone interested can easily find another thread where people who actually replaced their O2 sensors discuss these problems in more detail so I won't repeat them here.

That said, I will add a couple tips that may be helpful to someone who does this job.

First, you may find that the O2 sensors are so tight that you can't remove them even with a breaker bar. In that case, heat them up with a torch. I use MAP gas and the sensors then come out easily. I was lucky today because the front sensor came out without applying heat. Of course, you also need the special O2 removing tool. Don't get the slotted O2 socket. They open up under the stress. Get the other kind as shown in your service manual illustration (above).

Here's a trick I use but I never heard of anyone else doing it. Take a piece of string about 8 to 10 feet long and tie one end near the connector end or the O2 sensor end. Then pull out the O2 wire harness from the other end. When you put the new sensor in, tie it to the string and pull it into the original routing from the opposite end. That can be important and it can be almost impossible to see how it was routed originally, let alone be able to reach up into that pathway. You can do this from either end.

You will find that there are little nylon clips that attach to the O2 cable and snap into chassis parts to hold the cable in place. Don't try to pop them open to remove the cable while the old O2 cable is still in the car. Instead, with a screwdriver, pop them out of the holes they snap into in the chassis or whatever part they are snapped into. Remove the old O2 sensor assembly with the nylon clips still attached to the cable. Now, lay the new O2 sensor assembly next to the old one and mark where the clips should go. Then remove them from the old cable and snap them onto the new O2 cable. They will now be in exactly the position then need to be and it's much easier to pop them off the cable when they are on your bench instead of trying to do it in a hard-to-reach location on the car.

Be sure to use the special grease that comes with the sensor or an equivalent high-temp grease when you install the new O2 sensor.

Unlike some people, I found the downstream (secondary) sensor to be much easier to replace than the upstream (primary) sensor. The problem with the front sensor is finding and disconnecting the connector which is very hard to get at or work with. The engineer who decided to put the front connector where it is should be beaten severely, IMO. All he or she had to do was have a slightly longer cable and mount the connector in a more accessible place.

As for your "instructions," I ran across another post where you do did the same thing. In most cases, having a copy of the service manual section about a repair procedure would be helpful but, in this case, it's almost totally useless because the manual doesn't show you how to actually do the job. It basically just tells you to DO the job. If you actually did replace the sensors, especially the front one, you would have known this. For example, the manual doesn't even show where the connectors are or mention that the upstream O2 sensor must be removed from the bracket and that can be an incredibly frustrating job. If you did the job, you know that and it's hard to understand why you wouldn't have mentioned that in your post. Maybe you just replaced a downstream O2 sensor (?)

I've been working on cars since 1966. I have always done all my own work and still do. The front O2 sensor on a Honda Pilot is one of the most frustrating jobs I can remember. It is certainly not a case of just ... "1) Remove sensor --- 2) Reverse step one." I would suggest that you include helpful hints based on your own experience rather than just copy the manual in the future. Anyone planning to do this job can find more detailed information about how the job is actually done by a Google search that will come up with threads in other forums on the subject. Your post is certainly short but it is far from sweet. In fact, it's really all but useless because you just repeated what the manual says and the manual is useless in this case.

 

I have a 99' Honda accord lx vtec 4cy. And I just recently started having problems with it. I've been trying to diagnose using google and my manual but I keep hitting road blocks.
My car was running good until a few weeks ago when I accidently drove through deep water that stalled the car, but it started right back up and then a few days later started acting funny. I.E. when its cold outside its hard to start, after the engine warms up its hard to start. it turns over but won't catch. It's also throwing codes for p1259, p0302, p0303, p0304, p0430. yet a day ago my check engine light which had been on for a unrelated EGR problem went off.
The reason i'm posting this here is a mechanic friend told me it might be a o2 sensor. Any help you might be able to offer would be greatly appreciated.

 

Thanks ZoneIII for detailing the in between steps that were missing in "Disconnect the HO2S 4-pin connector (A), then remove the HO2S (B)".

I am attempting to replace B1S2 and B2S2 and hope this will help me with the job. Has anyone try splicing the wiring cables and attaching to the new sensor without removing the connector and cable? Are the wires solid or braided? I mean, if this is so much work, can you not just cut the old wires from the cable without removing the connector and solder them to the new wiring of the O2 sensor? You can use heat shrink other insulation to wrap them or tie them together. Will there be any issues? And leave enough slag in case another replacement down the road. It probably won't look pretty, but no one care what look like under the truck anyway.

 

just a heads up, those who purchased sensors other than honda, expect them to fail in about 45 days or less.

 

Replaced both front and rear O2 downstream sensors on my Ridgeline. It was painful but worth it.

The sensors are made by NTK $110 at Autozone each (NGK and NTK are same), they are original equipped sensors. Length as well as plastic attachments are also at the right place. Dealer quote $600 just to replace the rear sensor.

Here is what I learned. I used a short O2 sensor wrench to remove the front O2 sensor, but on the rear sensor, the wrench went inside the hole and no room to turn. End up buying a longer O2 sensor wrench. So I have both. You could get a whole set on Ebay for $30.

You will get more room if you loosen or remove the bracket holding the connectors, as already mentioned prior in posts.

You need small hands with strong finger or finger nails. You will hear it click. You may get frustrated hearing click again and connector gets locked again. You needs patient.

The rear sensor was more difficult. You need to remove the exhaust line to get access. Which means replace the metal seals on the front and back three way catalytic converters and new lock nuts. I got those from Honda for $40.

I think Honda shops use specialized wrench, may be curved handle. Definitely 10" long nose pliers will help with taking off or installing the cable.

Once the sensor is loosen, you can just use your finger to unscrew it. It just needs the first shock to loosen it.

My torque wrench is too big to fit in so I didn't use torque wrench to tighten, just guess it.

Get some old pillow or sofa cushion to lay on top of the engine. Get rest when you get cramp. Step ladder to climb up and down. Use steel ramp to raise the car when working under car to get more room.

I did not have to cut or splice the cable, although I was thinking about it during installation. There are some solder filled shrink wrap connector that they use for boating which may reduce dirt/moisture/salt getting into the wire. I don't know how the added resistance will effect the sensor or the engine computer response. Any comment?

 

I bought mine from Rock Auto, not Honda, and they've been working perfectly for several years now. I get a lot of parts from Rock Auto these days. They have about a dozen or more O2 sensors listed for the Pilot.

Thinking about it, I've never bought an O2 sensor from a dealer or the manufacturer of the car and I've had excellent luck with them. Besides, like most things these days, most O2 sensors are probably made by only a handful of companies and you can probably get the exact same sensor with a different label. What's weird is the wide range of prices. I just checked Rock Auto and the prices for O2 sensors for the Pilot run from about $35 to over $300! O2 sensors are very simple devices. There probably is some difference in quality between the high-priced and very low-priced parts but it's probably not as much as the price difference would indicate. I usually buy something in the middle with good ratings.

Anyway, from my experience, I can say with confidence that and O2 sensor purchased from a source other than the car manufacture is not doomed to fail. After all, that after-market sensor may very well be the exact same sensor that the dealer will sell you for far more - just in a different box with a different label.

 

Replaced my Ridgeline Rear Downstream o2 sensor
Bosch O2 sensor from Amazon for $5x.xx
O2 Sensor Wrench Kit Amazon $11.xx
Articulating Ratchet Socket Wrench Harbor Freight $14.xx
Propane torch
car ramps & jack stands
PB Blaster
Good worklight
Extension Mirror Amazon $8.xx

Tips:
- Give yourself a few hours at least - take your time
- Rear Downstream Sensor is up in a very tight spot (you have maybe 1-2 inches of movement for socket)
- DON'T need to remove exhaust to get to it.
- SPRAY PB blaster a couple days ahead of time
- HEAT joint with propane torch
- UNCLIP connector up top first (pull down wire to beneath car)
- upper wire connection is equally difficult to see/reach. Use mirror and light to discover which one (usually you can trace orange o2 wire coming up behind engine from under engine).
- remove bracket at back/middle beneath intake manifold to get to connection
- multiple connectors on this bracket
plastic o2 sensor connector is clipped into a socket AND clipped to the bracket.
- the square rectangular open slot on connector (look at new one to orient yourself) is what connects it to bracket. push tab connects it to connector.
- remove bolt to free bracket, twist bracket around to get to connector. unclip
Might have to break lower hold tabs which route the wire through behind engine. drop unconnected wire down to below.
- Get under car to remove sensor itself.
- Must use Offset O2 Sockets specifically for this purpose
- Use longer socket wrench with correct leverage angle to crack it free (hard to tell)
- Use smaller socket wrench with multiple articulating joints to get correct angle and leverage. May have to take socket off and reposition many times.
- May have to move body to get correct hand angle to remove o2 rest of the way by hand.
- O2 wires make it very difficult to turn as they get bound up - cut old sensor wire off or work around so you can turn.
- reverse process to install.

 

Thanks for the info.

 

I found replacement to be a royal pain. You’ll want both types of O2 sockets.