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TCS light on and O2 sensor bad---

P

Pirana

Contributing Member
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14 January 2005
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202
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First I have a 1995 OBDII, I got this code:

OBDII P0155--Front Primary HO2S Heater Circuit Malfunction (Bank 2 Sensor 1)

Now my question is, which one is it....when they say front, do they mean the bank by the firewall? Do NSXs have 4 sensors, 2 pre-cats and 2 aft-cats?


My second problem arouse after a dyno pull, where the TCS stayed on, the operator forgot to reset it after the first pull. When I got the car back the yellow TCS light on the right side of the cluster stayed on.

The OBDII scanner didnt pull any TCS codes...I tried resetting by disconnecting battery for about 2 days, but as soon as the car turned on the TCS came back on. I have read most of the TCS threads here already, any suggestions or ideas before bending over to dealer?

Any help would be greatly appreciated.
 
OBDII cars have 4 Oxygen sensors. You have two cats, and there is one sensor in front and one sensor behind each cat.

OBDII P0155--Front Primary HO2S Heater Circuit Malfunction (Bank 2 Sensor 1)

'Front' just means ahead of the cat...now, which cat is it? Bank 1 is the forward bank next to the firewall, Bank2 is the rear bank.

So, your rear-bank-upstream-of-cat sensor (or its wiring) has a problem. By any chance, did you just have exhaust work or headers installed? If so, its pretty easy to not have a connector properly seated.

The TCS issue is different, and I believe the codes are reset by simply pulling the clock fuse for a few seconds. I don't think TCS codes are output on an OBDII scanner. To retrieve TCS codes, you need to install the 'service jumper' (paper clip) on the connector located in the passenger footwell, then key on (not start, just lights on the dash) and count the TCS blinks.
 
NSXT said:
OBDII P0155--Front Primary HO2S Heater Circuit Malfunction (Bank 2 Sensor 1)

'Front' just means ahead of the cat...now, which cat is it? Bank 1 is the forward bank next to the firewall, Bank2 is the rear bank.

So, your rear-bank-upstream-of-cat sensor (or its wiring) has a problem. By any chance, did you just have exhaust work or headers installed? If so, its pretty easy to not have a connector properly seated.
Click to expand...

With respect, I would have to disagree with this. "Front" is the front cylinder bank closest to the firewall and "Primary" means BEFORE the cat(in the exhaust manifold), according to the 1995 service manual Page 9-4.

Page 11-159 shows the "Secondary" 02 sensor, AFTER the cat.

HTH,
LarryB
 
Eiffel, thanks for the info...just took the car to Acura, they will replace the O2 and one catalytic converter. Also if the car had 75k miles or more they would have done a complete tune-up free of charge. :redface:
 
Hello and help...I have been getting a PO420 code lately according to the manual it is the rear catalytic converter efficiency below threshold. If it is correct about 95's being covered for 14 years the dealer would fix this with a new TWC. The problem is intermittent though it has come up about every 500 to 1000 miles. I guess it could be a exhaust leak. Any thoughts on or experience with this problem.

Thanks in advance
 
Yes, its correct....14 years/150k miles under the extended emissions warranty. They just replaced my O2 and a bad catalytic converter ($1400~$1600) just for the cat. So take it to your dealer and get in checked out. My cat destroyed itself and damaged the O2.
 
Last edited:
My O2 sensor is being replaced even as I type this. The response I get from the Acura dealer is that the warranty is a 14 year/150k mile BLANKET warranty on anything related to the Check Engine light (at least for '96). If the light goes on, the repairs are free.
 
Well I dont know about everything with a CEL, because a bad Trottle Position Sensor can throw a cel but it should be covered under your normal 3/36k, but anything related to emissions is covered.
 
I want to thank all those who had let me know about the warranty for the emissions system. I had the cat and o2 sensor replaced today and by knowing about this info ahead I made sure the service rep checked it out and he had said that he had never heard of the warranty until I showed up. Well they haven't had the chance to work on to many NSX's. The rep told me that after looking into the warranty that there are about 7 pages of parts that are covered. The dealer is now more informed and my car is fixed, I think every one is happy. :smile:
 
anyone have a layout of the fuse box?
I have a CD of the NSX manual but the picture of the fuse box does not show which one should be the 20 amp fuse.
I just have the picture of fuse 1-8 with #3 being empty

Which one is the clock fuse?
 
Great information as I have an 02 sensor out now.

nsx2tall -- did your dealer tell you an official name of the warranty or a reference number? I expect a lot of blank stares when I go to my dealer and want to have as much information as possible.

NorCalWhite -- same question. Do you have the official name/reference number of the warranty?
 
amg_nsx said:
Great information as I have an 02 sensor out now.

nsx2tall -- did your dealer tell you an official name of the warranty or a reference number? I expect a lot of blank stares when I go to my dealer and want to have as much information as possible.

NorCalWhite -- same question. Do you have the official name/reference number of the warranty?
Click to expand...
It is called: Emissions Warrenty Extension TSB 98-031. Try Nalley Acura 770 422 7817. They will know what you're taliking about. HTH. Eiffel
 
It must be contagious because mine threw up a CEL and the TCS light came on after I left my car sitting for about a month. I noticed a lot of moisture in the exhaust. I pulled the code borrowing a OBDII code scanner from Autozone and it came up P0139 which is Rear Secondary Heated Oxygen Sensor slow response. I had them replace 2 of the O2 sensors about a year ago so maybe the 2 other ones are going bad.
 
Malibu,

Record the code, and reset it(pull the 7.5 amp "Clock" fuse. located in the fuse box on passenger side wheel well/front) Due to the moisture you describe, and the fact it has been run and dried out, this code may not re-appear. Time will tell:).

I am pretty sure if you bring it to the dealer this is the first thing they will do. Then decide if warranty is applicable. If the code does not reappear for them, it just may be a wasted trip to drop it off.


HTH,
LarryB
 
Larry Bastanza said:
Malibu,

Record the code, and reset it(pull the 7.5 amp "Clock" fuse. located in the fuse box on passenger side wheel well/front) Due to the moisture you describe, and the fact it has been run and dried out, this code may not re-appear. Time will tell:).
Click to expand...

Thanks Larry, I tried that last week and it keeps coming up. Once it came up when I was really pushing the car, now it will come up a few seconds after I reset the the ECU. I think that qualifies me now for the new free O2 sensor. :) Still a lot of moisture and I have a new tank of gas.
 
Malibu Rapper said:
It must be contagious because mine threw up a CEL and the TCS light came on after I left my car sitting for about a month. I noticed a lot of moisture in the exhaust. I pulled the code borrowing a OBDII code scanner from Autozone and it came up P0139 which is Rear Secondary Heated Oxygen Sensor slow response. I had them replace 2 of the O2 sensors about a year ago so maybe the 2 other ones are going bad.
Click to expand...


That could be it for me, since I only drive my nsx like once a month. The code was P0135 heated O2 Sensor 1 heater circuit. I hate going to the dealers, since I have to make two trips there. First they pull the codes, then order the parts. Then I go back to have the new part installed. Oh well, it's all worth it for the NSX! :rolleyes:
 

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