What's your o2 sensor story.

mr2tim · 09-16-2008, 12:38 AM

When my o2 sensor wires fell onto the exhaust pipe I discovered:
the heater section of the 4 wire type sensors carry a very large amount of electrical current in order to heat up the sensor tip.

Like maybe enuff to fry other parts of the electrical harness or the ECU?

Additionally, if you drive in deep water and get your sensor wet it may be toasted for good, or if you blow a head gasket and pass water thru the exhaust?

What kind of story would you like to share about your Code 21 experience?

jholder · 09-16-2008, 12:49 AM

Quote:

Originally Posted by mr2tim

What kind of story would you like to share about your Code 21 experience?

I'm throwing a 21 on a jdm swap. So far (still resolving it), when i bench tested the sensor, it was sending the proper voltage and dropping just like it should. I think it hates me. I had a few unconnected wires i *hoped* were the o2 sensoe, but they weren't. Soooo, gonna have to trace back the old fashioned way and see where the short is

jnfrizzell · 09-24-2008, 03:29 PM

i have a code 21 also on a 91 jdm swap i just replaced the o2 sensor when i went to get the sensor napa's system showed it was suppose to be a 4 wire but mine is a 1 wire i'm using a US ecu so that might be part of the problem. the car runs fine but i don't want it running with a CEL light on. anyone else?

Timon · 09-26-2008, 09:14 AM

Quote:

Originally Posted by mr2tim

Additionally, if you drive in deep water and get your sensor wet it may be toasted for good...

I don't really have an o2 sensor story (yet), but I sure would like to hear more about this one ^.

jnfrizzell · 09-26-2008, 12:14 PM

it looks like this is pretty common on a jdm swap where your using usdm and jdm componets the usdm uses a 4 wire heated o2 sensor and the jdm one uses a 1 wire non heated so the basic fix is have matching engine harnesses and ecu's if your useing a jdm harness and ecu get the universal 1 wire if your using a usdm harness and ecu get the 4 wire.

MR2SW22 · 10-30-2008, 03:30 PM

i got a weird story for you, i was installing my 3" DP the other day at work (honda dealership AKA the dark side) and i went home and car ran fine after i put everything back, rather i thought i hooked up everything. i forgot to hook up the 4 wire connector for the O2 sensor, funny thing is, the car ran fine, my CEL did come on, but it always does after a little driving do to the speedo cable not making a connection with the back of the stock gauge cluster. all and all i don't think i did any damage but i wonder if everything ran fine because im running a US91T motor and a 91-92 JDM ecu?

jholder · 11-07-2008, 11:34 PM

Quote:

Originally Posted by MR2SW22

i got a weird story for you, i was installing my 3" DP the other day at work (honda dealership AKA the dark side) and i went home and car ran fine after i put everything back, rather i thought i hooked up everything. i forgot to hook up the 4 wire connector for the O2 sensor, funny thing is, the car ran fine, my CEL did come on, but it always does after a little driving do to the speedo cable not making a connection with the back of the stock gauge cluster. all and all i don't think i did any damage but i wonder if everything ran fine because im running a US91T motor and a 91-92 JDM ecu?

As I understand it, the mr2 ecu, when faced with an o2 sensor issue, automatically starts running rich (heh, richer than normal if thats possible) as a safety feature. It makes sense of course, to default to safe mode if something happened like that.

I'm pretty sure thats the behavior, but now that I'm trying to locate where I read that I'm not able to find it. Maybe I'm smoking the crack rock.

MR2SW22 · 11-07-2008, 11:44 PM

Quote:

Originally Posted by jholder

As I understand it, the mr2 ecu, when faced with an o2 sensor issue, automatically starts running rich (heh, richer than normal if thats possible) as a safety feature. It makes sense of course, to default to safe mode if something happened like that.

I'm pretty sure thats the behavior, but now that I'm trying to locate where I read that I'm not able to find it. Maybe I'm smoking the crack rock.

all i have to say is... your mom on crack rock - Google Video

jholder · 11-08-2008, 10:19 AM

Quote:

Originally Posted by MR2SW22

all i have to say is... your mom on crack rock - Google Video

*ahh* 90s rap.

i need to buy a pimped out jetta with 14s!

mr2tim · 11-09-2008, 03:13 PM

That's smart engineering because if your engine runs lean for any amount of time danger exists for piston failure big time. Burning a hole in a piston will certainly make for a bad weekend and a big dent in the 'ol wallet.

As I understand it the incoming air charge loaded with heavy fuel cools the piston, without this cooling from the fuel excessive heat builds rather quickly.

Quote:

Originally Posted by jholder

As I understand it, the mr2 ecu, when faced with an o2 sensor issue, automatically starts running rich (heh, richer than normal if thats possible) as a safety feature. It makes sense of course, to default to safe mode if something happened like that.

I'm pretty sure thats the behavior, but now that I'm trying to locate where I read that I'm not able to find it. Maybe I'm smoking the crack rock.

09-16-2008, 12:38 AM	#1 (permalink)
mr2tim SUPERcharZed ToyZ RacZer Join Date: Mar 2008 Location: South Florida Posts: 690 Thanks: 2 Thanked 41 Times in 38 Posts My Google Map iTrader Rating: (2/100% )	What's your o2 sensor story. When my o2 sensor wires fell onto the exhaust pipe I discovered: the heater section of the 4 wire type sensors carry a very large amount of electrical current in order to heat up the sensor tip. Like maybe enuff to fry other parts of the electrical harness or the ECU? Additionally, if you drive in deep water and get your sensor wet it may be toasted for good, or if you blow a head gasket and pass water thru the exhaust? What kind of story would you like to share about your Code 21 experience?

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09-24-2008, 03:29 PM	#3 (permalink)
jnfrizzell No Skills Join Date: Mar 2008 Location: madison TN Posts: 34 Thanks: 4 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	i have a code 21 also on a 91 jdm swap i just replaced the o2 sensor when i went to get the sensor napa's system showed it was suppose to be a 4 wire but mine is a 1 wire i'm using a US ecu so that might be part of the problem. the car runs fine but i don't want it running with a CEL light on. anyone else?

09-26-2008, 12:14 PM	#5 (permalink)
jnfrizzell No Skills Join Date: Mar 2008 Location: madison TN Posts: 34 Thanks: 4 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	it looks like this is pretty common on a jdm swap where your using usdm and jdm componets the usdm uses a 4 wire heated o2 sensor and the jdm one uses a 1 wire non heated so the basic fix is have matching engine harnesses and ecu's if your useing a jdm harness and ecu get the universal 1 wire if your using a usdm harness and ecu get the 4 wire.

10-30-2008, 03:30 PM	#6 (permalink)
MR2SW22 Just add water! Join Date: Aug 2007 Location: Diamond Bar, CA Posts: 1,750 Thanks: 47 Thanked 25 Times in 24 Posts iTrader Rating: (6/100% )	i got a weird story for you, i was installing my 3" DP the other day at work (honda dealership AKA the dark side) and i went home and car ran fine after i put everything back, rather i thought i hooked up everything. i forgot to hook up the 4 wire connector for the O2 sensor, funny thing is, the car ran fine, my CEL did come on, but it always does after a little driving do to the speedo cable not making a connection with the back of the stock gauge cluster. all and all i don't think i did any damage but i wonder if everything ran fine because im running a US91T motor and a 91-92 JDM ecu?