O2 sensor

[Dragonlady]

Does anybody know the part number for the O2 sensor after the cat from the front bank?

Cheers Ian

ps Honda want £453.46 fitted!!!!!!!!!!!!!!!!! Holy he11

[Kaz-kzukNA1]

Hi, Dragonlady. Probably, you haven't checked the email yet.....
I sent the following info around midday today.....



++++++++++++++++++++++++++++++++++++++++++++++++++
Thought you may want to keep the CEL info so I'm sending this email.

CEL Error code: P0161
Front Secondary Heated Oxygen sensor heater circuit malfunction
(Bank 2, Sensor 2)

This is the sensor located at the front bank and after/downstream/post CAT. It is monitoring the performance of the CAT. Because it's an open/short failure in the heater circuit of the O2 sensor, the CEL will stay ON even after you cleared it unless you replace the sensor itself.

I always buy the sensor from US.
www.sparkplugs.com (http://www.sparkplugs.com)

The CAT spec is different between US and UK market so the OEM parts no. is also different. The difference is the cable length.
For your NSX, the OEM parts # is 36541-PR7-J51 but this is not used on Acura NSX and instead, they are using A51 as the last 3 digits.

From other UK owners who bought the replacement O2 sensors from US with exactly the same failure code, they managed to install it without having issues with the cable length despite the fact that there is no cross-reference available for the J51 spec sensor.

I saw some of the actual installation using the replacement sensor and you may need to modify the routing slightly but not much depending on the selection of the manufacture such as NTK or Denso.

The replacement sensor from Denso is #234-4093 at about US$66.
Cable length is about 580mm.

The one from NTK is #24633 at about US$96.
Cable length is about 470mm.

OEM sensor from the factory is Denso but I prefer NTK as I know them through F1 project (....... hidden for IP reason ..............).
Also, some of the US vendors such as SoS states that NTK sensor lasts longer than others.

Please note that if you changed the layout of the exhaust header/cat/backbox, you may need extension cable although you may have already using it if that is the case.

Regards,
Kaz

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As mentioned many times in my blog and posts on here, please be careful when ordering any parts around/related to the exhaust area from US.
The introduction timing of OBD2, emission regulations, etc are different that you can't order the parts by simply entering the year model, engine spec, body type, etc based on UK model info on the US parts site.
Basically, the same rule applies to any non-US models such as EU, Japan, Australia, Malaysia, etc models.
I know several owners and even the vendors making this mistake resulting in wrong spec O2 sensor and parts delivered.

Kaz

[duncan]

All,
My understanding is that the sensors have two separate elements [no pun intended], a heater and a sensor.
The heater is necessary on initial start up to get the sensor to an operating temperature, thereafter the heat of the exhaust gas kicks in. If that is correct, then the sensor can only be giving an incorrect reading for [say] the first 5 minutes.
If that is the case, other than to satisfy an MoT test their should be no need to get upset about a heater malfunction.
Comments from anyone?
Duncan

[Dragonlady]

All,
My understanding is that the sensors have two separate elements [no pun intended], a heater and a sensor.
The heater is necessary on initial start up to get the sensor to an operating temperature, thereafter the heat of the exhaust gas kicks in. If that is correct, then the sensor can only be giving an incorrect reading for [say] the first 5 minutes.
If that is the case, other than to satisfy an MoT test their should be no need to get upset about a heater malfunction.
Comments from anyone?
Duncan

Hi Duncan,

I understand what you are saying but the problem is that without changing the sensor the CEL will not reset, therefore you will never know if there is an additional problem in the future.

Sharon

[Mistercorn]

That and the fact you need it for the mot.

MC

[britlude]

i see where Duncan is coming from (essex lol!) did the CEL fire at start-up, or after the engine was warm?

just wondering as it'll give a clue to it being the heater or sensor... not that it'll make a lot of difference as the whole unit gets changed anyway.

i'd be inclined to start up and get everything up to temp, then stop, reset CEL, restart car and see what happens! but that's just me!!

is mot imminent?

.... multiple issues should give multiple error codes.... what you need is a nice accord to buzz around in, i've heard they are nice and reliable :)

[Kaz-kzukNA1]

All,
My understanding is that the sensors have two separate elements [no pun intended], a heater and a sensor.
The heater is necessary on initial start up to get the sensor to an operating temperature, thereafter the heat of the exhaust gas kicks in. If that is correct, then the sensor can only be giving an incorrect reading for [say] the first 5 minutes.
If that is the case, other than to satisfy an MoT test their should be no need to get upset about a heater malfunction.
Comments from anyone?
Duncan
From O2 sensor point of view, that is correct [Edit: as far as there is no CEL].
Once the exhaust temperature gets high enough, ECU will reduce the duty cycle of the heater control current.
[Edit: However, if the heater element failed and triggered the CEL, it will ignore the duty control].

From the ECU point of view, as far as I know, the sensor reading from the secondary O2 sensor is not used for the fuel timer adjustment at the era of NSX so the failure on secondary side should not affect the engine control but it still goes into fail safe operation. [Edit: Thus, as far as I know, that side of the bank won't go into closed loop control even after all the required conditions were met so the target A/F will be always on the rich side and won't be able to re-generate the CAT. Not good for the performance.]
It is used only for the monitoring of CAT performance and thus, in a very one-sided view, it is not even required to have the secondary O2 sensor on the car.

However, from a certain point of view such as environment, even for a short period of unknown state of emission control is not accepted. Thus, the CEL stays on until you fix the issue even when the primary O2 sensor alone can control the mixture.


i see where Duncan is coming from (essex lol!) did the CEL fire at start-up, or after the engine was warm?

just wondering as it'll give a clue to it being the heater or sensor... not that it'll make a lot of difference as the whole unit gets changed anyway.

i'd be inclined to start up and get everything up to temp, then stop, reset CEL, restart car and see what happens! but that's just me!!

is mot imminent?

.... multiple issues should give multiple error codes.... what you need is a nice accord to buzz around in, i've heard they are nice and reliable :)With P0161 code, it's open/short circuit of the O2 sensor Heater circuit and not the sensor head so fairly easy to check with the multimeter if you can access the connector mounted at the edge of the rear valve cover.
Since it's open/short circuit, even if you clear the error code by pulling the CLOCK fuse or through the OBD2 scanner, the CEL will come back immediately after starting the engine.




For LEV model, Honda is even pumping the fresh air into the exhaust port in order to speed up the heating up process of CAT temperature to minimise the harmful exhaust elements to protect the environment.
You will see big air pump behind the side air duct with lots of pipes, tubes, valves, etc in the engine bay resulting in increase of the weight that is against the concept of NSX.


You will find similar story on the A/C system when the R12 is much more efficient compared to R134a or even the latest next generation gas R1234yf.

In this era, environment consciousness seemed to win over the performance, cost and efficiency.

Kaz

[Dragonlady]

Kaz and his fountain of knowledge saves the day again and a lot of money. We cannot thank him enough, unfortunately after arriving at the Honda garage we were told that our normal mechanic who is NSX technician was on leave despite having purposely asked for him to replace the O2 sensor. As a result some numpty decided to have a go and didn't know what they were doing.

As a result they said that the sensor was the wrong one, so we went to a local Honda specialist and took Kazs notes and they fitted the sensor no problem.

So we can make our way to Italy now this evening knowing the car is fine. Thank you Kaz.

Sharon