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DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low
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rainbow123
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PostPosted: Sat Sep 17, 2005 6:41 pm    Post subject: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

could somebody shed some light on this error code please? i want to fix it myself if i can, i googled "MAZDA MPV P0051" and nothing came up, thanks
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subearu
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PostPosted: Sat Sep 17, 2005 7:39 pm    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

According to http://www.mpvclub.com/diy.php?id=56 it's the Front LH side O2 sensor.

There is a thread here http://forum.mpvclub.com/viewtopic.php?t=6424 that talks of diagnosis on the RH front sensor.

-Brian

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rainbow123
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PostPosted: Mon Sep 19, 2005 2:33 am    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

thank you, the info in that thread is very helpful, i checked today there is no continuity on terminals C and D, i suspect the O2 sensor heater is shot, my van only has 27000 miles, isn't it a bit early for the O2 heater to go bad?


the light first came on around 20000 miles, so it's been running on a 02 sensor with bad heater for 7000 miles, that sensor probably sent out false (lean?) signal before it had a chance to warm up, has it already done irreversible damage to the left side pre-catalytic converter? thanks again
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2003MPV-LX
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PostPosted: Mon Sep 19, 2005 6:40 am    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

that's very early for an 02 sensor to go bad. is it still under warranty for age?

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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mazda-fla
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PostPosted: Mon Sep 19, 2005 12:13 pm    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

If it is still under warranty, then just take it to the Dealer to worry about.
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rainbow123
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PostPosted: Mon Sep 19, 2005 12:14 pm    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

2003MPV-LX wrote:
that's very early for an 02 sensor to go bad. is it still under warranty for age?


it's 2000, and out of warranty, any chance they'll replace it for free? I want to save $59 and some elbow grease
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2003MPV-LX
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PostPosted: Mon Sep 19, 2005 12:17 pm    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

i think i would contact mazda and at least ask. since it is an emission related part, they might. usually an 02 will last well past 100K.

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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mazda-fla
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PostPosted: Mon Sep 19, 2005 12:35 pm    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

Get it replaced right away, either you, Dealer, or independent mechanic.

When you get a check engine light for sensor 1 (before the pre-cat), the computer puts the car in "open-loop" mode. Basically to get you home. When you are in open-loop mode, the car runs the default air-fuel mappings. These default mappings are rich.

Over the long term, the rich conditions will ultimately ruin the pre-cats. Both pre-cats will be ruined, because both will be getting the rich mixture.

Chances are this has not yet occured on your van. Just get that sensor replaced as soon as possible.

Usually people ruin the pre-cats after running like that for several years. Hopefully, a few months like that and you will still be okay.

Also, if you want to save a few bucks, get the generic O2 sensors at www.oxygensensors.com . You have to cut off the pigtail connector from your existing O2 sensor, and splice it onto the generic 3-wire or 4-wire O2 sensor. The generic sensor comes with the splicing kit (crimp style connectors and heat shrink tubes). All you need is a pair of wire cutters and a match or lighter for the heat shrink tubes (maybe 15 minutes of work).


Last edited by mazda-fla on Mon Sep 19, 2005 12:40 pm; edited 1 time in total
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rainbow123
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PostPosted: Mon Sep 19, 2005 12:36 pm    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

thanks, you are right i never had a bad 02 sensor on my previous cars, but then they do not have heater, does the heater circuit have a high failure rate?

to mazda-fla, at what miles your right front 02 sensor heater (P0031) fail?
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mazda-fla
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PostPosted: Mon Sep 19, 2005 12:43 pm    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

Mine failed at about 45,000 miles.

Even though you have low mileage, you do have several years on them. It also depends on what kind of gasoline you use in the car. If you live in an area that uses high sulfur content gasoline, that will deteriorate the O2 sensors quicker. Also, if you use premium gasoline, the higher concentration of additives will also deteriorate the O2 sensors quicker.

O2 sensors don't last that long in today's cars. You can expect that they have to be replaced every few years.
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rainbow123
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PostPosted: Mon Sep 19, 2005 1:44 pm    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

mazda-fla wrote:
Get it replaced right away, either you, Dealer, or independent mechanic.

When you get a check engine light for sensor 1 (before the pre-cat), the computer puts the car in "open-loop" mode. Basically to get you home. When you are in open-loop mode, the car runs the default air-fuel mappings. These default mappings are rich.

Over the long term, the rich conditions will ultimately ruin the pre-cats. Both pre-cats will be ruined, because both will be getting the rich mixture.



thanks for the advice, is it correct to assume you can have the heater fails but an otherwise functioning 02 sensor?

for example, the p0051 says only heater and/or circuit fails which does not mean the 02 sensing part itself is not working fine once it reaches operating temp, therefore it would only affect the time before the engine warms up and slows its entry into closed loop, and once it warms up, PCM would turn off heater anyway and enters into closed loop, so just the heater failing is not the same as the 02 sensor failing outright, and i would assume less serious

nevertheless, i have to replace it right away because it would fail the smog
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MartinP
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PostPosted: Sat Sep 24, 2005 2:54 pm    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

rainbow123,
you are probably right, I currently have P0057 in, same as P0051 except it is on sensor #2 (or Rear/after the Pre-Cat).
If the engine is hot and I erase the MIL, MIL wouldn’t come back as long as the engine is hot (since OBC will switch heater OFF ), only on the cold start when heater in ON, will MIL come back. So in theory we are running with not functioning O2 sensor only during first few minutes, till the engine (and the sensor) get hot enough.
I am in the process of replacing the sensor right now, if it work, I'll post the outcome.
Cheers
Martin
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MartinP
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PostPosted: Sun Sep 25, 2005 10:00 pm    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

I finally replaced Bank2 Sensor2, it is actually easier than changing the Oil Filter (definitely less messy), it's located right beside the filter. Challenging parts were:
1) Getting replacement, if you don't want pay for OE, I end up getting Bosh Universal that comes with neat solder-less connector to connect with the original Mazda connector for about C$105 (Mazda OE is about C$175).
This is list from Bosch site:
15256 Oxygen Sensor - OE Type Before Catalyst Front
15259 Oxygen Sensor - OE Type Before Catalyst Rear
15733 Oxygen Sensor - Univ Type After Catalyst Two required
13596 Oxygen Sensor - OE Type After Catalyst Rear
15730 Oxygen Sensor - Univ Type Before Catalyst Two required
15257 Oxygen Sensor - OE Type After Catalyst Front
http://www.boschusa.com/AutoParts/FAQs/OxygenSensors/
2) Disconnecting connector
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nls
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PostPosted: Mon Sep 26, 2005 9:11 am    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

MartinP - what year is your MPV? I have a 2000, and am still trying to correlate the Bank 1/2, Sensor 1/2 with the left/right, before/after catalytic converter. A diagram that was sent to me showed three before the cat - left front, right front and middle, and one after the cat - see my post in http://forum.mpvclub.com/viewtopic.php?t=10182. Fortunately my CEL has not come on after the second reset, and I am hoping that the codes were because of something in the gas, or for some reason other than a bad sensor.
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rainbow123
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PostPosted: Mon Sep 26, 2005 1:11 pm    Post subject: Re: DTC P0051 - H02S Bank 2 Sen 1 Heator Circuit Low Reply with quote

martinp, i saw your sensor when i changed my front left, yeah the rear left is definitely very accessible, the front left is harder, i cut the wire and slip in a box wrench, though there wasn't much leverage there, it came off suprisingly easy, but putting it back on was more difficult, i think i made the mistake of splicing the wires before screwing it back in, with the long cable i couldn't screw it in, and also could not use the box wrench, i didn't want to cut it up so i ended up having my wife twisting the harness on top as i screwed the thing and also had to borrow the compact sensor tool from autozone

i paid $52 for a walker universal from oxygensensors.com the wire colors are the same, i didn't go for the Denso because the OEM is Denso but failed at 20000 miles, i just read http://forum.mpvclub.com/viewtopic.php?p=29490#29490, i can probably get by with an equivalent ford one from ebay cheaper next time
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