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Oxygen Sensor after Warranty Expired

50K views 41 replies 19 participants last post by  howardc64 
#1 ·
The "Check Engine" and "VTM-4" lights came on for my '03 MDX (58K miles) last week. :( Since I have not purchased any extended warranties, I want to see what others experienced out there. After researching the various threads, there were a great deal of useful information. Thanks to ALL who post. KEEP IT UP! Most of the posted items are emissions related and covered under the emissions warranty (8/80).

I learned that AutoZone will read the codes for free. :D They scanned the OBD and found a P0134 code for "O2 Sensor, CKT No Activity, (Bank1)(Sensor1)". I later learned from a dealer that this is the upper rear oxygen sensor located on the exhaust manifold closest to the firewall. Official Acura Part number / description = 36531-RCA-A02 / Sensor, LAF. The part replacement is made easier with the appropriate tools for compact areas. I have attached a diagram. (If I can figure it out right.) I will also attempt to post a couple of photos as well.

Here's a couple of other threads I posted to and checked out:
Check Engine Light/Vtm-4
Check Engine+MisFire == Spark Plugs?

Who has had the bad Oxygen Sensor issue outside of the basic warranty (4 yr / 50K mi) and a dealer covered it as a warranty item? Do you think this is an item that should be covered by Acura?
 

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#5 ·
Here's an attempt at a wider angle view. This picture includes the engine cover. Use a 10 mm under the 'green' circled covers to remove the entire engine cover. The particular oxygen sensor (Bank1 Sensor1) is by the fire wall as indicated with the 'red' box. The view is not all that better with the engine cover removed.

Was there anything specific you are looking for?
 

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#7 ·
Thanks Redwingz.

As you have time, that would be a great resource to have. One argument Acura may have is the different model years - 2002 vs. 2003. But what the heck, let's give it a try. I think it's worth a try to recoup ~$150 for the part alone. Hopefully, it references only the part and/or part number. That should increase my chances.
 
#10 ·
Redwingz said:
For the oxygen sensor problem, I thought there was a recall by Acura (MDX) a while ago. I have a 2002 MDX and thought I saw some type of notification about the oxygen sensor....I could be wrong but if you want me, I can try look it up.
This may be too late. Sorry I was out of touch with the forum for a while. I will look it up and see what I have. Maybe it can be useful for others... sorry mate!
 
#11 ·
Redwingz said:


This may be too late. Sorry I was out of touch with the forum for a while. I will look it up and see what I have. Maybe it can be useful for others... sorry mate!
Was that O2 sensor from Acura for $150?? wow, that's really expensive for a tiny part. Is that any equivalent from Bosch? My 03 has 45k so I am thinking about changing that for maintainence. But for $150 I need to think about that.:eek:
 
#12 ·
Bosch Equivalent

In checking the Autozone website, I did find what appears to be an equivalent ... Bosch / Oxygen Sensor, Part # 15401, $124.

Application: Rear converter, Sensor located before catalytic converter
Note: O.E. type, 5 wire, wideband

Their product photo appears to be very similar.

Good luck in your personal case.
 
#13 ·
Re: Bosch Equivalent

Jupiter said:
In checking the Autozone website, I did find what appears to be an equivalent ... Bosch / Oxygen Sensor, Part # 15401, $124.

Application: Rear converter, Sensor located before catalytic converter
Note: O.E. type, 5 wire, wideband

Their product photo appears to be very similar.

Good luck in your personal case.
Thanks, looks like there are 2 sensors before cat converter & 1 after, dam## , why they put so many sensors? I will probably get from the dealer for only 15% difference.
 
#14 ·
For that small of a difference, I decided to go for the OEM part.

There are actually FOUR (4) oxygen sensors in the MDX (at least the 2003 model). I will post a diagram next week.

There is one after the catalytic converter and three before the catalytic converter. There is one immediately before the cat. and the other 2 are on the exhaust manifolds of the engine.
 
#16 ·
Jupiter,

You've obviously replaced a few O2 sensors in your day! I am told by Acura that the VTM light is on because my "front" o2 sensor is bad. I am quite handy with tools and I'm sure I can replace the part myself...if I can find it! Since there are 4 sensors, and they all look the same, how do I know which one is the "front"? I see it's #10 in your diagram, but since the diagram is sort of a zoomed in, I don't know where in the engine compartment it is located. Help!

Thanks!
 
#17 ·
oxygen sensor problem

I had the same problem on my 03 MDX. Dealer said the warranty had expired (41,000 miles, but over 4years in service). I bought a sensor socket and Bosch 15401 sensor ($99 + tax & $10 for the socket at Autozone) and replaced the sensor myself. The problem was solved. The biggest problem was disconnecting the old sensor from the connector socket. The sensor socket assembly must first be removed from its horizontal blade mount. There is a plastic tab on the inner face of the socket. Pull the tab away from the mounting blade and pull the connector assembly to the left (towards the sensor). The disconnect the connectors, held by the same type tab. good luck
 
#18 ·
Jkallen1,

Truthfully, this was my first oxygen sensor I replaced ever and by myself. It was a real pain in the a$$ to get the 'rear' sensor off. This was primarily due to the reach and extreme close quarters.

Check my last replay on 5-18-2007, it mentions the locations of the O2 sensors. I believe the 'Front' sensor is located before the catalytic convertor on the manifold system at the front of the vehicle closest to the radiator. Depending on your relationship with your dealership, the service folks may confirm/validate the location for you. ;) If this is the case, it will be slightly easier to reach. :2: Good luck and keep us posted. By the way, the diagram was courtsey of Acura (I will not detail the dealership).
 
#20 ·
oxy sensor

Jupiter,
The P 0134 fault is bank 1 / sensor 1 as you determined. It is a 5 wire sensor. After consulting several sources I determined the (less expensive) Bosch replacement was the 15401. The Acura dealer had quoted $146 plus tax. Although I normally would rather use the original equipment parts, I took a chance on the Bosch sensor. It is working so far (500ish miles)
 
#22 ·
Well - it's all done. I replaced the o2 sensor before the catalytic converter. The "front" one as they say. I wanted to share my experience.

1) I opted for the Universal Bosch because it was the only one in stock at every place I went. Pep Boys was cheapest at $59. I would recommend against this Universal route. It really wasn't fun. I probably spent an hour with the 2 sensor checking and double checking my wires, cutting and splicing, and connecting. But it was cheap! You can buy these new on ebay for $50 - $100. Acura dealers use Denso brand and I saw those on ebay too.
2) I "borrowed" the socket from Autozone - really cool tool loan program they have. You just leave a deposit and get to use the tool for free essentially. If you don't bring it back, you bought it. I will be taking mine back as soon as I finish this post javascript:smilie(':)')
3) How many sensors are there? Acura tells me there are only 2 - on the 2001 a least. I saw someone saying 4 in another post - I'm not sure how you could get 4 on the exhaust line or why it would be needed.
4) Jupiter was correct on the pictures he posted about where the sensor wire is. Note that the sensor is underneath the car, very visible on the manifold - and you kind of have to start there and follow the wire up to locate the connector. You MUST disconnect the connector and free the wires before you remove the old one. This is done from the engine compartment - back of the engine near the firewall. I suppose you could cut the old wires off underneath and then remove the sensor since you won;t be using it anymore. But if you have the universal, you must leave about 5 inches of wire on the connector end.
5) Not sure why it matters, but many kits talk about a 29 inch wire. The Acura wire is 20.5 inches (including the sensor).
6) I had to disconnect the negative battery terminal to correct the "Check Engine" Light. And I want to ask you guys about this:
2 weeks ago, the maint reqd light came on. I know this is a normal 5K "change oil" light. Before I reset that light, a week later, the vtm4 and check engine lights came on. so when I changed the sensor, all 3 lights were on. After changing the sensor, the check engine and maint reqd lights were on - the vtm4 light went off on it's own. I did the normal maint reqd reset sequence and then just the check engine light remained. The battery pull fixed that last light. What I want to know is....is that normal? I mean for the vtm4 to go off by itself and I had to reset the check engine myself? Also, is pulling the battery the only way to do that?

Thanks guys!
 
#23 ·
Some great info. Thaks for all the comments.

Couple questions. Just threw a P2247, which indicates bank 2 sensor 1 (oxygen sensor). I know it's the front sensor, but can anyone clarify if this is top or bottom? I think it's top as it says sensor 1. Bank 2 means front?

Also, the Bosch number is 15730, a universal model. Has anyone replaced a front sensor with this universal one? All go OK?

Final question. I have to assume these are easier to get out when they are hot. I see they're only torqued to 33 ft lbs, but I'm sitting with 83,000 miles so I'm sure it's seated well.

Thanks.
 
#24 ·
BlueStreak,

Since your MDX is also an '03 model, your part references should be exact to what I have posted.

I do know that the one I replaced - Bank 1 Sensor 1 - was the rear upper sensor closest to the fire wall. My "GUESS" would agree with you that Bank 2 Sensor 1 is the front upper sensor closest to the radiator. I would suggest contacting your local dealer service center to validate our thinking.

Good Luck. Let us know how this works out.
 
#25 ·
Jupiter said:
BlueStreak,

Since your MDX is also an '03 model, your part references should be exact to what I have posted.

I do know that the one I replaced - Bank 1 Sensor 1 - was the rear upper sensor closest to the fire wall. My "GUESS" would agree with you that Bank 2 Sensor 1 is the front upper sensor closest to the radiator. I would suggest contacting your local dealer service center to validate our thinking.

Good Luck. Let us know how this works out.
I was just able to confirm the bottom sensors (front and rear) are referred to as "secondary", so bank 2 sensor 1 is the top one close to the radiator. Bank 1 is the rear, closest to the firewall.

The Bosch universal 15730 unit is a 4-wire unit and my top sensor has 5 wires. So I'm researching how to do this now. The unit may have instructions in it, but I wanted to validate this before I went and bought one. Looks like pin 1 is relay, pin 2 is heat, pin 6 is voltage in, pin 7 is pump cell and pin 8 is ground. The Bosch units appears to be internally grounded. So I may be all set...
 
#26 ·
Some useful information

I've learned a lot the past 24 hours re: o2 sensors aka A/F (air/fuel) sensors. I'll recap from the begining to help everyone.

1. There are two different o2 sensor types - regular and wideband. Regular is 4-wire and wideband is a 5 wire. The 2003 MDX uses 5-wire for the top sensors primary inside and outside. (bank 1 sensor 1 and bank 2 sensor 1)

2. You can not use a 4-wire regular sensor in place of the wideband. While the Bosch book lists this, it will not work. Need TWO signal pins from the wideband unit. Don't try to share a single signal wire from the sensor to two wires on the X harness.

3. There are TWO different o2 sensors listed for the 2003 MDX. Bosch part number 15730 is listed as a universal and 14501 is the wideband. Someone posted the Acura part number of 36351-RCA-A02. On the bag of my sensor from Bosch is listed this same number. So the Acura part number must be the Bosch part number.

The 15730 Bosch part IS the replacement for the secondary o2 sensors, and both the front and rear secondaries are the same. So it's two parts to replace all four sensors, a 15401 and 15730 for the inside (top and bottom) and same for the outside set-up.

4. The wideband part is 80.99 from AdvanceAutoParts. So buy it there and save from the Acura price. It was a plug and play device. The regular 15730 sensor is 61.00.

To install, it's faily easy. PUSH the locking tab on the connector and pull the connetor a part. Rent the puller from $10 from an auto parts store and the sensor broke free. Simply un-thread. The car was warm, but not hot.

Screwed in a new unit and I was ready to go. 33 ft. lbs of torque to tighten.

Hope this helps.

P.S. The Bosch tech I talked to knew his stuff and was of great help. 888-715-3616 is their number. I had to leave a message, but they called back in less than 5 minutes.
 
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