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Old 02-13-2006, 07:08 PM   #1
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Now im getting frustrated!

So after finally ordering a new MAF today to take care of my CEL codes,P1123 and P1125 another code is thrown at me P0134(02 Sensor CKT No Activity(Bank 1 Sensor 1)). Could this be a result of the bad MAF in my car?

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Old 02-13-2006, 07:22 PM   #2
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Bad 02 sensors can throw off the MAF and give funky readings that are very hard to diagnose. I had a bad sensor that made the PST tool indicate that the MAF was malfunctioning. My mechanic swapped the failing sensor with an old one he had lying around his shop and the MAF readings started looking good again.

How many miles do you have on your boxster and what year is it?
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Old 02-13-2006, 07:30 PM   #3
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53k on a 99. I had a quick peak under the car and located all four o2 sensors. Now the question is how hard are they to change?
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Old 02-13-2006, 08:06 PM   #4
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super easy and you're certainly due. They're to be changed at 60k.

www.oxygensensors.com

OEM Bosch sensors with the right connectors for $119 each or something close to that. If you have a floor jack, you can do it with normal tools and some grunting and at least one bloody knuckle in 45 minutes.

A $10 02 sensor offset slotted socket made it really easy for me.

Change out all four (required) plus your MAF and you should be CE light free for a long, long time. Plus, you'll get better fuel economy and possibly more power if you disconnect your battery afterwards for about a half hour or less. (this makes the DME recalibrate the system, which includes rough idling for a little while).
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Old 02-13-2006, 08:17 PM   #5
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If I do not have the funds for all four is it possible that I run a month or two with 3 old and one brand new? Is it possible that just the o2 sensor wiring should be check ed to make nothing came loose? Does anyone have any directions on accessing the o2 sensors,more specifically taking them off and reconnecting?
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Old 02-13-2006, 08:23 PM   #6
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One brand new one will be overly sensitive and the others dull, making for lousy fuel economy, really bad performance, more CE lights and who knows what. I guess it's possible, but I've been warned over and over by my own mechanic and people on lists everywhere not to do it.

Drive the car "as is" if you can, grit your teeth every time you see that CE light, and save up enough to swap out all four asap.

Thank goodness you don't have to change these out all the time, huh?
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Old 02-13-2006, 08:25 PM   #7
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Taking them off is easy. Unscrew them.

But, you have to unplug them first, and this is done by carefully putting the blade of a flathead screwdriver into the locking side of the connector and twisting to get it to pop the male part out of the receptacle. It really is quite easy, and when you get your new ones you'll see how to open them up and you'll say "duh, that's no big deal"
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Old 02-13-2006, 08:48 PM   #8
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I can physically see the sensors but where do the wires run to?
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Old 02-13-2006, 08:57 PM   #9
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Up to where they plug in! On the back ones, you'll have to peel back the heat shield to see the plugs. On the front ones, there is no heat shield and you should be able to see the plugs with a flashlight.
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Old 02-13-2006, 08:57 PM   #10
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Swap all 4!!!!!!! Not doing so will keep the CEL on. Trust me...I went through this very recently.
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Old 02-13-2006, 10:50 PM   #11
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How long could I last with CEL P0134 on without damaging the car? Im not cheap or trying to push it off but I dont have money to spend after several purschases,rear speaker kit,MAF and a whole bunch of CDs(I wouldnt have bought the kit and CDs if I would have known this would happen). With code P0134 stating 02 Sensor CKT No Activity(Bank 1 Sensor 1)),should I check to see if the plug came loose first before ordering a new set? After my new MAF shows up should I install it clear the CEL and see if P0134 comes back on?
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Old 02-14-2006, 06:07 AM   #12
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When Your Ready Blinkwatt I Have Oem O2 Sensors At $115 Or Universal O2 At $89 The Universal Need To Be Spliced Into Existing Harness
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Old 02-14-2006, 06:29 AM   #13
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Quote:
Originally Posted by blinkwatt
How long could I last with CEL P0134 on without damaging the car? Im not cheap or trying to push it off but I dont have money to spend after several purschases,rear speaker kit,MAF and a whole bunch of CDs(I wouldnt have bought the kit and CDs if I would have known this would happen). With code P0134 stating 02 Sensor CKT No Activity(Bank 1 Sensor 1)),should I check to see if the plug came loose first before ordering a new set? After my new MAF shows up should I install it clear the CEL and see if P0134 comes back on?

Hi,

Certainly you should determine if it's a wiring problem or a Faulty O Sensor because if it's in the wiring, a new Sensor won't fix it. Do you have a multimeter? If so, you can check continuity. With the Sensors removed, you can Bench Test these as well (see my previous post on Testing O Sensors). If you have exceeded, or are approaching 60k mi., replacement is a good idea anyway.

So far as driving the car with the issue present, you won't be helping the Car. The DME will go into a default MAP, running rich, on adjusted Timing. The Car's Performance and MPG will suffer. In addition, the less than optimal A/F Mixture can potentially cause damage to the Cats (Much more expensive than a couple pair of O Sensors).

It used to be that to an extent, you could ignore a Faulty Emissions System. But, in Today's Cars, the systems are so intertwined that all sorts of negative effects can be realized. Get it fixed as soon as you are able. Hope this helps...

Happy Motoring!... Jim'99
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Old 02-14-2006, 08:25 AM   #14
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It aint a loose wire. The connectors are far too sturdy for that. You'll see what I mean when you replace them.

Borrow some cash from a friend or family member and get them replaced if you must drive the car back and forth from work.

Porsche, there is no more expensive German subsititute.
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Old 02-14-2006, 10:33 PM   #15
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Well I talked to a local independent shop today and they said if it is the o2 sensors and I dont have money for all four,I should be able to at least order a pair and change out the ones before the cats. Then I can later order the other o2 sensors after I have more money. The shop is higly recommended for Porsche work but I have never personally used them. Does this information sound realible? By the way MNBoxster you should be teaching car classes,your o2 sensor thread us amazing. Is there a way I can test them without a blow torch though?
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Old 02-15-2006, 07:20 AM   #16
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Quote:
Originally Posted by blinkwatt
Well I talked to a local independent shop today and they said if it is the o2 sensors and I dont have money for all four,I should be able to at least order a pair and change out the ones before the cats. Then I can later order the other o2 sensors after I have more money. The shop is higly recommended for Porsche work but I have never personally used them. Does this information sound realible? By the way MNBoxster you should be teaching car classes,your o2 sensor thread us amazing. Is there a way I can test them without a blow torch though?
Hi,

Personally, I can't see replacing only the Fronts as a solution. The reason for this is that the DME compares the readings between the Front and Rear O Sensors, and then Bank to Bank, to determine what MAP to select. You could actually create worse problems. It would arguably be better to replace one entire side, but maybe only slightly because again, the DME could go into Default MAP from the other side alone. Are the codes you're getting relative to one Bank of Cylinders? Or worse from one side? But, you still won't be doind the Car any favors driving it this way. As mentioned, see if you have someone who can Spot you the Cash, this would be best.

There is a Test which you can do on the Car, but it's not, IMHO, any easier. Here are some fast and reliable diagnostic procedures which you can use to check out the O Sensors in situ.

The following symptoms will help tip you off to a failed oxygen sensor:

Surging and/or hesitation
Decline in fuel economy
Unacceptable exhaust emissions
Premature failure of the catalytic converter

You will need the following equipment:

A handheld volt meter (digital VOM or Digital Multimeter)
A propane enrichment device, such as a Propane Torch (Unlit)
An oxygen sensor socket

It should take less than 10 minutes to perform a diagnostic check.
  • 1. Verify the basic engine parameters, integrity of the electrical system (supply voltage), fuel delivery, mixture performance and internal mechanical considerations (eliminate any other possible causes for the poor running condition).

    2. Treat the rich mixture performance as follows:
    a. Disconnect the O Sensor lead to the control unit.
    b. Run the engine at 2500 rpm.
    c. Artificially enrich the fuel mixture by directing propane into the Side Intake until the Engine speed drops by 200 rpm. Or, with electronic fuel injection, you can remove and plug the vacuum line to the fuel pressure regulator.
    d. If the voltmeter rapidly reads .9 volts, then the oxygen sensor is correctly sensing a rich mixture. But, if the voltmeter responds sluggishly, or if it stays below .8 volts, then the sensor should be replaced.

    3. Test the lean mixture performance as follows:
    a. Induce a small vacuum leak.
    b. If the voltmeter rapidly drops to .2 volts or below in less than a second, then the oxygen sensor is correctly measuring the lean mixture. But, if the voltmeter responds sluggishly, or if it stays above .2 volts, then the sensor should be replaced.

    4.Test dynamic performance as follows:
    a. Reconnect the sensor lead.
    b. Set the mixture to specification.
    c. Run the engine at 1500 rpm.
    d. The sensor output should fluctuate around .5 volts. If it doesn't, replace the sensor.

Diagnosis

To check the performance of the oxygen sensor, run the vehicle engine at about 2000 rpm to ensure that the sensor remains hot throughout the test procedure. Do not remove or disconnect the sensor lead in order to test it as this will eliminate the "closed loop" signal to the DME and result in a non-cycling voltage condition. Connect your test leads so as to read voltage from the signal wire to the DME. With vehicles that use a heated oxygen sensor such as the Boxster (four wire), it may be necessary to bridge the connector leads and tap into the signal wire with an appropriate test probe at the connector plug in order to obtain the signal. The Multimeter will allow you to read the electrical response of the oxygen sensor to changing exhaust gas oxygen content as a measure of its performance.

A properly functioning oxygen sensor will exhibit a rapidly fluctuating voltage signal alternating between approximately .2 and .8 volts in response to varying residual oxygen content in the exhaust stream. Look to your scope's time reference line for a desired lean-to-rich and rich-to-lean time of less than 300 milliseconds. A response time greater than 300ms. means that the sensor should be replaced.

It is important to recall that these values are valid only when checking a sensor operating in "closed loop" in a hot exhaust stream (350-800C). Sensor age, degree of contamination, mixture setting, and exhaust temperature all have an effect on response time.

Without this rapid electrical response to changing exhaust composition, the DME cannot accurately correct the fuel mixture. A sluggish sensor is either contaminated or beyond its intended service life and must be replaced. Hope this helps...

Happy Motoring!... Jim'99


Last edited by MNBoxster; 02-15-2006 at 07:22 AM.
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