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2003 LL Bean - Code 51, replaced o2 sensor, car won't start

LL Bean code 51 o2 sensor car wont start

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19 replies to this topic

#1 nfosnowkats

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Posted 24 May 2014 - 09:00 PM

The title pretty much explains it. 

 

Hubby replaced the battery today and the o2 sensor (based on a code 51 reading).  He then tried to reset the code with the engine running and found out that he wasn't supposed to do that.  I don't know if that is the problem, but now the car will not start.  I think it is "dead" and doesn't even try to turn over.  I will correct that if he tells me differently. 

 

I need to be able to get to work and get my car tags, but cannot due to the check engine light.

 

Help, please :-).



#2 Fairtax4me

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Posted 24 May 2014 - 09:23 PM

Code p0051 generally means there is a voltage problem going to the sensor.

Codes can be reset with the engine running. Doesn't hurt anything.
The no start problem sounds like the battery cables are not attached properly.

#3 nfosnowkats

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Posted 24 May 2014 - 09:29 PM

Hubby says that is not an issue.  However yes, there was a battery issue longer than the check engine light was on. 

 

Indeed the engine does nothing.  Overhead light does not come on and dash readings are dim.  So yes, seems like battery.  But could it be a fuse?  Battery is brand spanking new. THis is the process for today:  It was installed.  Car turned on to get down ramp, car turned off.  Car turned on to use code reader, for about 5 minutes.  Code did not reset.  Car turned off.  Car would not restart.



#4 grossgary

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Posted 24 May 2014 - 10:33 PM

1. Battery is defective (a defective new battery is nothing new to hear of)

2. The end terminals are warn or not tight enough - if you can twist them by hand they're not tight enough.  if they're corroded, they need cleaned.

3.  Battery cables themselves.  Corroded, poor connection

 

some very easy tests:

1. check battery voltage (though it may not have enough amps or have dead cells)

2.  jump the car with cables and another car (have to ensure excellent connections)

3.  run jumper cables - positive to the positive node on the starter to see if it'll spin. that will give it a quick hard bump - only do it for a second as a test.

 

given your symptoms it's almost pointless to guess or suggest anything else until those are checked out.



#5 nfosnowkats

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Posted 25 May 2014 - 04:16 PM

So hubby is trying again. 

 

I don't know if we're back to the o2 sensor code 51 issue now.  We don't have an ECU fuse.  He checked all the fuses and they are all good.  We have tried jumping it and it at least responds now, but won't turn over.  We have not checked battery voltage.  Not sure if we have a voltimeter.  Haven't tried funning to the starter.  Terminals were cleaned when the battery was replaced.  Battery started the car without issue 3 times (max run time though was 5 minutes), then would not start at all, no charge, no nothing.  Cables look good, but hubby has not unwrapped them or gotten under the car to check them at the other end.

 

What fuse should we pull to reset the code 51? 

 

What can we do to get the car started?

 

Edit - Just checked the volts and they are about 12 as they should be.


Edited by nfosnowkats, 25 May 2014 - 04:21 PM.


#6 1 Lucky Texan

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Posted 25 May 2014 - 06:35 PM

maybe exercise the key fob's lock/unlock sequence a coupla times. Could be some kind of security issue?



#7 Fairtax4me

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Posted 25 May 2014 - 09:13 PM

Pulling fuses will not help. If the code is still present after clearing with the scanner its because the fault is still there.
Need to check the wiring to the rear O2 sensor.

I've seen brand new batterys fail in one day so its not impossible, but terminal connection problems are very common.
If the tops of the battery posts don't stick out above the cable clamps, the cables aren't attached properly and could be making poor contact with the posts.

#8 nfosnowkats

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Posted 26 May 2014 - 10:57 PM

So, an update.  The new battery seems to work, at least for 2 starts :-).  I made sure to run it about 45 minutes (30 of that driving) in one consecutive time, then the next time was only about 10-15 minutes. 

 

However, the check engine light is still on.  Have not checked the code or tried to reset it (since the first fiasco), so don't know if it is the same code or a new one (like the other o2 sensor). 

 

Interesting response above about the security system, as when the new battery was installed, indeed the security light was flashing, so I went through and locked/unlocked a few times, however the light kept flashing, but did not cause any problems when I started the car.

 

Realistically, it will probably be next weekend before hubby looks at my car again.  I'll update then. 

 

Thanks all for your help.  It's nice to have a place to ask questions and get good answers!



#9 1 Lucky Texan

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Posted 26 May 2014 - 11:07 PM

maybe it's in valet mode or ???



#10 CNY_Dave

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Posted 29 May 2014 - 07:51 PM

What's the voltage at the battery with the lights etc on?

 

The H6s get very funky when the alternator starts to go.



#11 nfosnowkats

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Posted 29 May 2014 - 10:45 PM

Current status...

 

On Tuesday, the battery died as I was turning off the car (the click in between on and off).  There is a shop (for big trucks) at my work and they pulled my battery, put it on the charger, tested it, tested the alternator, which were both good.... then they cleaned the cables which were corroded (although hubby didn't think so).  However, that seems to have solved the battery issue.

 

I am wondering though... my security light is on now when the car is not running and when I use the fob to unlock my car, the lights no longer flash.  Subaru said that the security light should have been on (for the last 11 years I've owned the car).  Hmmm.  I don't know ?  Please let me know.

 

Also, the code reader apparently got killed when hubby killed replacement battery #1, as he went to read my code last night and the reader was dead.  So he got that replaced, read my code, reset it, but then when I started the car this morning, the check engine light was on again.  Presumably the same code.  I don't know if the new o2 sensor is bad or ? 

 

So that's where I am now on Thursday evening.



#12 1 Lucky Texan

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Posted 29 May 2014 - 10:48 PM

security system could be in valet mode or ???



#13 nfosnowkats

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Posted 29 May 2014 - 11:01 PM

Right, I checked into that with your first post.  That's why I called Subaru.  They said that the security light SHOULD BE flashing when the ignition is not on.  I'm not so sure it should be.

 

I have a couple of print outs on how to take it out of valet mode, but it doesn't look to be a simple one step process and the directions are different and I don't know if it is in anything but the "correct" mode currently.



#14 1 Lucky Texan

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Posted 29 May 2014 - 11:03 PM

I never paid much attention as to when the flashing stops, i assumed it was when I hit the unlock button on the fob.

 

but, it definitely flashes when activated.

 

3 rapid flashes seems to be valet mode according to;http://www.cars101.c...ess.html#alpine


Edited by 1 Lucky Texan, 29 May 2014 - 11:06 PM.


#15 Gloyale

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Posted 01 June 2014 - 02:31 PM

Perhaps the Running lights switch on the top of the steering column is on? 

 

That would keep the running lights on.....unable to flash....and would also drain the battery.

 

FWIW......Our 2003 LL bean H6 has a persistant code for O2 sensor bank 1 voltage issue........won't clear........tested all wiring end to end to the ECU.....replaced with new O2........code stays.......started around 170k miles and been on since (now at 230k).......

 

Assuming ECU problem...but since it runs we are not replacing the ECU.



#16 nfosnowkats

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Posted 01 June 2014 - 04:34 PM

Hubby replaced the o2 sensor, kept getting the same code, found a subaru forum that said "remember that this is a japanese car" (so what is left is right), so we replaced the wrong o2 sensor, as you probably did.  If you replaced the $70 sensor, now you need to replace the $200 sensor.  I take it that you don't have emissions testing in OR?

 

I haven't run my car since he replaced the 2nd o2 sensor, but I think all will be well now :-).



#17 coolcar2000

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Posted 02 July 2014 - 09:12 AM

i also have this code on my outback 2003 with h6 3.0l,,,

changed the sensor,didint work, cant find the main relay to check voltages,,,can you help me??



#18 1 Lucky Texan

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Posted 02 July 2014 - 10:00 AM

P0051 is front (upstream of the cat conv), left side (US driver's side) O2 sensor. dunno about the source of the power to it.

 

might be some help here; http://www.subaruout...eplacement.html


Edited by 1 Lucky Texan, 02 July 2014 - 12:49 PM.


#19 Gloyale

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Posted 02 July 2014 - 12:12 PM

Passenger side is bank 1  (the side with #1 cylinder....furthest forward on the crank)



#20 Cougar

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Posted 02 July 2014 - 01:20 PM

Here is the definition of code P0051: The heater control circuit voltage is too low on bank 2 sensor 1.

This means that the front sensor (before the CAT) on bank 2 (driver side of an American made Subaru) has too low of voltage on the heater circuit. Normally 12 volts is sent to the heater coil when the engine is cold. This heats up the O2 sensor faster to get it working correctly. It is likely that the new sensor wasn't installed correctly and is miswired. If power was mistakenly applied to the sensor output lead then the sensor could have been damaged and a replacement will be needed. If the wires are correctly connected then it would appear that there is a break in one of the two leads. The power side or the ground side of the circuit. Since the other sensors seem to work okay I have to think the power to them, which passes through the Main Relay, is good.





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