O2 code

OK on my 96 I have a O2 code of 138 (Bank Sensor2). But about 2 months ago I replaced my 02 sensor in the cat. I dont think that sensor is bad. The code is calling for sensor 2. Can anyone give me insight on high voltage code.

When my rear sensor went out I got a code 21. But my 96 may be a before the changeover model or an early 96 or something like that.
Maybe disconnect the battery for awhile, unplug the rear O2 sensor and see what code comes up. It may not be the sensor, but a stopped up cat or a dirty air filter, the supply voltage is low (dirty connector, cooked wire) or some other reason. If the sensor isn't getting enough oxygen (or even heat) it will pop a code also.

8Mud said:

When my rear sensor went out I got a code 21. But my 96 may be a before the changeover model or an early 96 or something like that.
Maybe disconnect the battery for awhile, unplug the rear O2 sensor and see what code comes up. It may not be the sensor, but a stopped up cat or a dirty air filter, the supply voltage is low (dirty connector, cooked wire) or some other reason. If the sensor isn't getting enough oxygen (or even heat) it will pop a code also.

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21 is the generic MIL O2 sensor code, which you can get from doing the key thingy. If you put it on a reader, it will give you a DRB code (P0138) that will tell you which sensor and what is wrong. (not sure what the correct terminology is, but it's probably some standard). In this case, it's reporting that the downstream O2 sensor voltage supply is too high.

I *think* this could be caused by a grounded heater circuit, but that's a guess.

Why did you replace the sensor in the first place, and have you inspected the wiring yet?

Ditto on the wiring. Check the pins in the connector. There is an intermediary piece that can allow the pins to get pushed out of place. Take a look at it and you'll see what I'm talking about.

Ok I replaced the sensor because the code came up 2 months ago. I guess I will have to check out the wiring. So you think my cat could be bad?

I was messing with my front sensor and after that it started giving me a code.
I think the wires going in got messed up.
I replaced it, which I was planning to do anyway with about 135K miles and it went away.

JIMBOJAMES said:

Ok I replaced the sensor because the code came up 2 months ago. I guess I will have to check out the wiring. So you think my cat could be bad?

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I just replaced the cat in my 96, 150,000 miles or so. There was no mistaking it was bad, it sounded like a tin can full of rocks, when you first started up.
When my rear O2 sensor started throwing codes, it didn't actually seem to affect the way the motor ran at all. I couldn't notice any difference, though my wife did mention the mileage was getting worse. My O2 senor had some sort of physical encounter, it was actually broken/cracked almost through near the base. Probably a branch I drove over popped up and broke it.
I've seen many pins back out of connectors and make iffy contact, on numerous occasions. I've gotten so it's something I look at closely and often pull and wiggle the wires some where they leave the connector, you can usually feel when they wiggle more than they should.
The 96 has a pretty good system to tie the wires from the rear sensor up out of harms way, but rub throughs and cable damamge are always a possibilty.
I've noticed the supply voltage for various sensors often has a common source, when one sensor messes up it affects the supply voltage for others. I'm not certain about the O2 senors though it is also likely.

8Mud said:

I just replaced the cat in my 96, 150,000 miles or so. There was no mistaking it was bad, it sounded like a tin can full of rocks, when you first started up.

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My 96 has 149K and it sounds like a tin can full of rocks, when you first start it up.
Is it possible that there is a self destruct mechanism in the cat that activates at 150K?

8Mud said:

I've seen many pins back out of connectors and make iffy contact, on numerous occasions.

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That's the reason I buy the sensors that include the connector instead of splicing in a generic.
Takes some of the posibilities to go wrong, out.

If you are to buy another O2 sensor, get an OEM one. All the aftermarket ones seem to not work after a short period of time. My brother had to replace one on his '90 Accord. Used a Bosch one and after about 30 days, check engine light back on, fuel mileage went back down. Spent more money on the Honda OEM one, never had a lick of problem after that.

Jeff

Voltage high also can mean the emissions are high, if the sensor is good and doing its job a bad cat will give a "voltage high" on the down stream sensor.

ihscoutlover said:

If you are to buy another O2 sensor, get an OEM one. All the aftermarket ones seem to not work after a short period of time. My brother had to replace one on his '90 Accord. Used a Bosch one and after about 30 days, check engine light back on, fuel mileage went back down. Spent more money on the Honda OEM one, never had a lick of problem after that.

Jeff

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In my experiences with Honda's, if you dont replace the honda part with another Honda part, its not gonna work very long. Still can't figure out for the life of me why Honda's are so damn picky about parts.

ihscoutlover said:

If you are to buy another O2 sensor, get an OEM one. All the aftermarket ones seem to not work after a short period of time. My brother had to replace one on his '90 Accord. Used a Bosch one and after about 30 days, check engine light back on, fuel mileage went back down. Spent more money on the Honda OEM one, never had a lick of problem after that.

Jeff

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Didn't Bosch manufacture the first sensors and have been doing it since then?
I use Bosch and never had any problems.
Besides, I refuse to pay dealer prices if I can help it.
Its a rip off. They charge large amounts of money for parts they don't make.
Good example the ball joints for D 30, I bought the same Spicer parts from a local 4x4 shop for a 1/4 of the dealer price.

falcon556 said:

Didn't Bosch manufacture the first sensors and have been doing it since then?
I use Bosch and never had any problems.
Besides, I refuse to pay dealer prices if I can help it.
Its a rip off. They charge large amounts of money for parts they don't make.
Good example the ball joints for D 30, I bought the same Spicer parts from a local 4x4 shop for a 1/4 of the dealer price.

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I believed this to be true until the dealer sold me a new PCM for $460 shocking that the dealer gave me a nearly $200 price break. And a crank sensor for $20 cheaper than Napa. I found that it depends on the part, but maybe I have a decent jeep dealer.


Check the heater circuit fuse in your interior fuse panel.