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O2 sensor change 2003 MPV
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johnchang7
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PostPosted: Sat May 22, 2010 1:17 pm    Post subject: O2 sensor change 2003 MPV Reply with quote

Hi has anyone changed their O2 sensors in a 2003 van? Can you list the procedure in which you did? The dealer said that its the left bank sensors 1 & 2 that need replacing. I looked at the engine today and I'm wondering if I need to remove the engine cover to get to it. Thanks John
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2003MPV-LX
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PostPosted: Mon May 24, 2010 9:12 am    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

The 02's are in the exhaust pipes. You will have to get under and take a look. They are visible, but I've never had to touch them yet.

2003 MPV LX, Emerald Mica, Rear Spoiler, Auto-Exe Grill, Fog Lights, hitch, Concept DVD w/twin headrest mounted 7" monitors, K&N, visors, splash guards, LIMO tinting on all rear windows. silverstars. Mama's Zoom-Zoom
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steve12955
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PostPosted: Tue May 25, 2010 12:48 pm    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

Hello,

On my CA emissions-spec '00 (even though I'm in MA), there are four sensors and they are accessible from under the car. The after-cat sensors are much easier to see and remove. The pre-cat sensors are located up high on the manifolds and are more difficult to get at. You'll need an O2 sensor socket or maybe an assortment of 13/16" open-end wrenches of various lengths but I've ended-up using both to change all four sensors at various times. The wire connectors are a bear to locate and disconnect - they seem to be buried in a mass of vacuum hoses and other wires on the top- and backside of the engine. Be diligent and follow the affected sensor's wires and you'll eventually uncover them.

Are you seeing codes leading to O2 sensor issues?

Good luck,

Steve
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Andrew Tremeer
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Location: Lawrencetown, NS, CA

PostPosted: Mon May 31, 2010 8:50 pm    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

I've got an O2 sensor code (bank 1 sensor 1)on my 2000 that is the front manifold I've looked at it and tried to get it, but it is awkward to reach and there is not a lot of room to move a wrench, and its well seized. Any chance of getting the same one of my spare parts van undamaged or should I bite the bullet and by another?
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ponderosaTX
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PostPosted: Tue Jun 01, 2010 1:35 am    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

2002 and later MPVs have the same O2 sensor layout as Steve mentions for his CA spec 2000 model. For 2002 and later MPVs, there is no distinction between CA and non-CA vehicles.

About 18 months ago, I replaced one of my pre-cat O2 sensors. The biggest problem was figuring out how to get the electrical connector to release. I bought an O2 sensor socket but did not use it. I was able to use a combination wrench to unscrew the sensor. Beware of using silicone lubricants anywhere including the electrical connector. Silicone can destroy O2 sensors. The MPV sensors breathe (draw in clean air) through their electrical wires.
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rajulshah
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PostPosted: Sun Sep 18, 2011 2:13 pm    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

steve12955 wrote:
The wire connectors are a bear to locate and disconnect - they seem to be buried in a mass of vacuum hoses and other wires on the top- and backside of the engine. Be diligent and follow the affected sensor's wires and you'll eventually uncover them.


Hi Steve,

I have a 2004 MPV and am trying to replace the o2 sensor 1 in bank 1. Did you have to remove anything from the top at all to get to the connector? Can you please describe better where it's located.

Thanks.
Rajul
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djsted
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PostPosted: Thu Sep 29, 2011 9:41 am    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

I, too have to replace my o2 sensors. It's totally confusing to me and hopefully I can get a better understanding.

2000 mpv
I call mazda with my vin and they said NOT california ..ok BUT they also said the all 4 of my sensors are BEFORE the 'Y' comes together. Meaning that the there must be 2 catalytic convertors (one for each branch of the Y) with a o2 sensor both before and after them.

My cat. is AFTER the Y, and I can clearly see 2 of the sensors ..one just before the cat and one right after.

The code reads "bank 1, sensor 2" - shopping online the terminology is 'upstream/downstream', 'left/right', 'passenger/driver side' - which is confusing to me.

1. how do i determine if the first owner put in a different exhaust system from the original such that I can't rely on mazda specs for o2 sensors?
2. Other than the connectors, are o2 sensors any different from each other... is the front o2 sensor any different than the back o2 sensor other than it's connection type?

I can pay someone $500 to do all four (parts and labor) but I'd rather buy online and do it myself for the $300 in parts it'd cost.

any help would be greatly appreciated.

thanks,
mike
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scross
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PostPosted: Thu Sep 29, 2011 1:53 pm    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

If you can read the fine print, the thread below has a diagram which calls out the locations of the sensors in the California vs. Federal models: http://forum.mpvclub.com/viewtopic.php?t=25759

But I think what it boils down to is this: if all you have is the LARGE cat(s) further back in the exhaust system, or if the large cat(s) have sensors just before and after them, then you have a Federal emission system. The California system adds (or maybe just moves the monitoring to) the two smaller cats up front. These are known as "warm-up" cats, by the way (WU-TWC - Warm-Up Three-Way Catalytic Converter, in the vernacular) because they are small and right at the engine and are supposed to warm-up and start doing their job very quickly after the engine is started. The bigger cat(s) in the back, in contrast, take a lot longer to get up to operating temperature and to start cleaning up the exhaust.

Bank 1 Sensor 2 SHOULD be the back side of the engine, and the sensor which is AFTER the cat. But if you have any doubts (and there may still be some room for confusion here, as shown in the thread I referenced), then just unplug that sensor and see what new codes you get (if any) after that.

I doubt seriously that anyone has made any major changes to the exhaust system, other than maybe simple, basic repairs. This would be expensive, more complicated than it looks (potential computer changes and what-not), and most likely also against the law.

AFAIK, most of the O2 sensors are in fact different part numbers, for various reasons. This doesn't necessary mean that you can't go with a much less expensive, generic sensor though, just as long as you take proper care to make high-quality splices. This is very important because you're dealing with very low voltages here, and a bad or aging/dirty splice can play havoc with these voltages.
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djsted
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PostPosted: Thu Sep 29, 2011 3:18 pm    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

wow! that was precisely what i needed to know! thanks so much scross.

Your image is exactly what I got from alldatadiy and I appreciate you using it as a reference - it's a great picture.

I'll have to look to see if there are WU-TWC's on my car (wow, I just sounded like a mechanic!) I'm pretty sure they are not. Which means a FEDERAL o2 sensor part for each of the 4 points.

The part I purchased may have been a California part which may account for the connection difference.

To use the markets terminology: I have 1 (downstream / after cat / rear) o2 sensor (located closest to the tailpipe),
and 3 'upstream' sensors:
1 'middle' o2 sensor (would that be bank 1 sensor 2 or bank 2 sensor 2?) and then the
2 remaining sensors near the top of the engine on either side (bank 1 sensor 1 and bank 2 sensor 1)

So as long as I stick to Fed sensors and ensure the connections are correct before I buy then I should be able to shop with confidence.

I've come across Partstrain.com which seems to have pretty good prices. If anyone knows of any defacto low price online shop then please let me know.

Thanks again.
Michael
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scross
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PostPosted: Thu Sep 29, 2011 7:32 pm    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

Glad to be of help. As far as what that "mystery" sensor is called, my suggestion still stands - just unplug it, then see what the computer calls it when it throws a code complaining about it. Based on the diagram, my assumption is that (whatever it's called) it's just there to be used as an upstream comparator for the cat, and that unplugging it for a short while will have absolutely no effect on the engine.
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carmenkeeper
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PostPosted: Sat Nov 30, 2013 11:52 pm    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

I replaced my front, pre-cat oxygen sensor in my 2003 MPV with a Denso 234-4209 part I bought online for only $36. The vendor offered a lot of 02 sensors to pick from, all supposedly fitting my year/model, for the price I paid up to over $80, and the dealer wanted over $120. I figured with that much money at stake, it was worth the risk to buy & return if it didn't work. In this case, luck was with me and it did work.
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rit14623
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PostPosted: Mon Apr 14, 2014 11:45 am    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

NEED HELP.

I changed out the two O2 sensors on the radiator side of the engine bay.
I tried to change them out on the firewall size of the engine bay with no luck. For the upstream O2 sensor, I could undo the socket connection but couldn't undo the O2 sensor. I could get a O2 sensor socket and ratchet on it but I couldn't get any leverage because the gap between the firewall and the steering rack was too small. For the downstream sensor, I could get the socket connection undone even though I could feel it. I couldn't depress the button to free it. Since this sensor is unobstructed, I had no problem loosening this one, but I didn't bother because I couldn't undo the socket.

1. I know they make a special ratchet for this, but even if I could seat it, I can't get leverage to pull on it. This is from below the van. I doubt that I could reach it from above between the engine and firewall.

2. How to undo the downstream sensor? For the front, I had this special tool that I could depress the release button, but in the back, I can't fit anything on the socket connection except my finger. There's this pipe in the way.
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owr084
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PostPosted: Mon Apr 14, 2014 12:06 pm    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

The last post in this thread offers a solution to getting the plugs undone. http://forum.mpvclub.com/viewtopic.php?t=23832&highlight=

For the upper sensor - you need to do it by braille. It is a pain to get out. What type of sensor removal tool are you using? The full socket type or the one that looks like a crow foot wrench that you use with an extension? The latter will allow you to use enough extensions to get clear of the intake. Also try wobble extensions. I

RBB
2007 Volkswagen Eos 2.0T
2005 Volkswagen Passat GLS TDI Diesel
2002 Mazda MPV ES
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rit14623
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PostPosted: Tue Apr 15, 2014 11:17 am    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

owr084 wrote:
The last post in this thread offers a solution to getting the plugs undone. http://forum.mpvclub.com/viewtopic.php?t=23832&highlight=

For the upper sensor - you need to do it by braille. It is a pain to get out. What type of sensor removal tool are you using? The full socket type or the one that looks like a crow foot wrench that you use with an extension? The latter will allow you to use enough extensions to get clear of the intake. Also try wobble extensions. I

Well, the front bank of O2 sensors have the same plugs as the rear bank of O2 sensors. So I know the upstream's sensor socket requires me to push on the end of the button to release. But the downstream's sensor socket requires me to push in the middle of the button to release. So after reading that link, it's a good idea to attach a string to pull on the wire with the left hand while the right hand is pushing down on the button.

I have a O2 sensor removal socket. It attaches to a 3/8 ratchet wrench and the other end is C-shaped so the wire can fit through and it is sized for O2 sensors. I jacked up a O2 removal on a Honda one day using a regular cresent wrench so I bought this thingy which has come in handy.

I'll try it again next weekend. I'm not getting any CELs. I'm just doing preventative maintenance as the van is reaching 90,000 miles.
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rit14623
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PostPosted: Tue Apr 15, 2014 11:20 am    Post subject: Re: O2 sensor change 2003 MPV Reply with quote

owr084 wrote:
The last post in this thread offers a solution to getting the plugs undone. http://forum.mpvclub.com/viewtopic.php?t=23832&highlight=

For the upper sensor - you need to do it by braille. It is a pain to get out. What type of sensor removal tool are you using? The full socket type or the one that looks like a crow foot wrench that you use with an extension? The latter will allow you to use enough extensions to get clear of the intake. Also try wobble extensions. I

So, regarding the extensions, you are suggesting to get the tool on the O2 sensor and then get leverage from above. I'll try that. I can hardly get my arm down there between the firewall and engine.
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