# Knock Sensor and O2 Sensor



## lolli (Jul 29, 2007)

Hi

My mechanic has been quoting a price of 814$ for replacing the Knock Sensor and O2 Sensor. Is this reliable or is he ripping me off.....Your help will be appreciated guys.

Knock Sensor - 185$
Labor Hours - 90$ per hour * 4.30 = 378$.

O2 Sensor - 161$
Labor Hours 1hour = 90$

Is this accurate???


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## brianw (Feb 25, 2004)

What year is your car?

His book labor rates look right, although if he really knows what he's doing, he can do it faster...


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## lolli (Jul 29, 2007)

brianw said:


> What year is your car?
> 
> His book labor rates look right, although if he really knows what he's doing, he can do it faster...


Hi Brian Thanks for the reply. It is 1998 Nissan Maxima. So is it genuine that he is taking 4-5 hrs to finish it???


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## brianw (Feb 25, 2004)

Knock sensor price and o2 sensor prices look like standard retail, labor rates look like standard book.

if he's NOT a Nissan specialist, see if you can find one-- or at least a GOOD, qualified import specialist. Knock sensor is possible to do faster than that, but you need to have super-flexible arms to get at it without removing the intake manifold-- it's not an easy job and many mechanics cannot/will not do it that way.

Also the knock sensor harness may be corroded, that should be replaced as well at the same time.


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## Maximangled (Aug 9, 2007)

*I've got to replace 02 sensor, then what?*

Hi Brian,

Nissan service tells me the 02 sensor needs to be replaced (for 767.50). Only then will they know if there is another reason why the Service Engine Soon light came on. When I asked him to give me a list and costs of what else might be wrong, he said he can't tell me. There could be 172 other things wrong. I feel like my car is held hostage. Don't know whether to proceed or make a charitable contribution of the car. 

Any advice?

97 Nissan Maxima with 132K miles.

Thanks,
Maximangled


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## mayfew (Aug 18, 2004)

Maximangled, do you know what O2 sensor needs to be replaced? you can purchase the part yourself(not from the dealership, they are expensive) if you do not know which one any auto pars store can check the code and tell you, then do it yourself to save money. they are very easy to change, only one bolt and a wire harness. then have any auto parts store clear the engine light, if it comes back on have them read the code and see what else is causing you problems. With that many miles that could be your only problem.


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## Maximangled (Aug 9, 2007)

mayfew, The code that came up was T0136. Does that tell you which O2 sensor? So far, I'm not a mechanic, though one bolt and a wire harness sound manageable. Perhaps the question I should be asking this forum is: how can I find a reputable repair shop with a labor cost about half the dealer's $125/hour, and someone who will direct me (as you just did) to buy my own parts cheap, etc. Thanks for the advice. I will take it.


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## mayfew (Aug 18, 2004)

To figure out which O2 sensor it is, you can ask ant auto parts store, and you can buy it from them too. Around where I live the NAPA seems to be the best. I would at least look at where the O2 sensor is located, the auto parts store should be able to tell you where it is located. I know that only one of the O2 sensors is in a tight spot, but the others are very east to get to( I am talking a 10-15 minute job for some one with little or no car knowledge). I you feel that you still can't do the job you can go to any "hole-in-the-wall" shop because, they are not going to be working in anything that requires Nissan expertise, O2 sensors are on all cars.


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## smj999smj (Jan 1, 2006)

PO136 is the rear oxygen sensor. TSB#NTB98-011a addresses the issue of PO136 codes on the 97 Maxima. Originally, the rear sensor screws into the pipe behind the catalytic converter from the left side. Nissan found that condensation was hitting the sensor and causing the element to crack, so they redesigned "center exhaust tube" behind the converter so that they sensor can be relocated at the top and less prone to this type of failure. The redesigned tube was standard on 98 models. You'll have to look and see if it's been updated or not. The redesigned setup takes a differant O2 sensor P/N as the harness is longer.

So, you have options: (1) install the original type rear sensor (P/N: 226A0-0L701) in the original type center tube (if that's what you have currently installed) and be prone to future problems of sensor failure, or (2) install the updated kit, which is a bit pricey (you'll need Service Kit# B0031-0L710, which includes an O2 sensor and a bunch of parts along with the updated exhaust tube), or (3) if you already have the updated center tube, you can just install the 98-style O2 sensor (P/N# 226A0-0L710).


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## smj999smj (Jan 1, 2006)

As far as the Knock Sensor, it can be replaced without removing the intake manifold but it's not easy...just easier. One would need a long 1/4" drive extension and a good, 12MM swival socket in 1/4" drive, 1/4" ratchet and a long, skinny screwdriver. I've done lots of them, but they are no picnic. That being said, the tech is quoting by a labor guide...so if he can get it done quicker, shouldn't he reap the benefits of making a few extra bucks on the job? THAT is the question of debate!


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