Oxygen Sensor Code 21

1994 Voyager 3.0 liter V-6, Mitsubihi engine, almost 199,000 miles.

This time when I noticed a Check Engine light as came to a red light. I thought, aha, this time, I shall look for a code. Thanks DS.

An anomaly, the car stalled out while driving slowly around 20-30 mph, after about 5 minutes. It has done this in the past. Had 2 1/2 gallons of gas left in the tank. Oil is full. Don't know why it does this, usually upon starting. Happens about once a month or two or three. Just stalls out. So while coasting, put in neutral, and restart the engine.

Checked the codes, pretty sure I saw 12 21 55. Not positive but pretty sure. Assuming the 12 and 55 are the Start and Stop code, 12 for a battery disconnect within last 60 starts, which seems unlikely, but okay, it's common for the codes to start with a 12.

So 21 is the:

21 Oxygen sensor signal doesn't change (stays at 4.3-4.5V). Probably bad oxygen sensor

I am wondering. Maybe low gas in the tank, too little pressure on the fuel pump might give this reading? The pump has to work too hard without fuel kind of boosting it a bit?

A genuine bad sensor? Have had this car for only the last 30,000 miles and don't recall any repairs for sensors in the repair records though. Have to look again.

I have the genuine, official Chrysler shop manual for this vehicle and a digital voltmeter, so could do a little poking around first. I heard the sensor is not too difficult to replace but to get the OEM part. Wonder what the price difference is. I replaced the thermostat with an OEM part which looked better made than the Slant and less likely to jam so worth three times the price, for less aggravation.

Any ideas here? THe car had a tuneup, new plugs and wires and that valve, PCV? Maybe something else? Would the dealer have a scanner giving more codes and info? Have to see how if the Check Engine is going to come on all the time or not.

Maybe throttle body cleaning, is that something I can inspect or is this one that is done by assumption? DS suggested that before but I have not noticed much in the way of stalling out after I posted that problem last year. My car apparently reads this newsgroup and behaves better after I complain!

Reply to
treeline12345
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replace the 02 sensor and clean the throtttle body

Glenn Beasley Chrysler Tech

Reply to
damnnickname

It's not doing it. Just once the Check Engine light came on. Only once. The "21" code is stored but that would be stored in any case?

If the oxygen sensor is bad, should not the Check Engine light be coming on while the car is running? Or so says the shop manual.

What do you think? Does Autozone actually show the voltages the O2 is supplying or not supplying? Do they really have a full computer hookup? Seems unlikely but I have heard they will scan but don't know what they scan with.

And replace it with the Bosch or with OEM? Or is the Bosch OEM? And this is the upsteam O2 sensor? It's the one that sits on top of the engine but I got confused when looking into carparts.com. 3 sensors with different part numbers but the same SKU! And 3 different prices. Wonder what the dealer charges. Somewhere in the same ballpark?

Thanks for your comment. I'm just being a little cautious here until things lighten up and I can just give the minivan to the dealer and say, fix it, regardless!

Reply to
treeline12345

When the 02 sensor does not switch for a certian amount of time the code is set, if it starts switching again the lite will turn off untill it acts up again

Stay away from Auto zone to diagnois your vehicle, they sell parts

The engine only has one sensor and I would use the OEM

It's the one that sits on top of the

Clean the throttle body and replace the 02 sensor and be on your way

Glenn Beasley Chrysler Tech

Reply to
maxpower

How old is the O2 sensor?

Probably. Replace it. It'll probably fix your stalling problem and certainly improve your mileage. Don't use a Bosch O2 sensor; they fail early and often. Pick an NTK, Mopar, ACDelco or Standard-BlueStreak. The O2 sensor socket (with the slot down the side) makes it easy.

No (but do keep on top of the fuel filter replacement schedule. Every 20k to 30k miles is good.)

Be advised that the O2 sensors get slow/lazy as they age, so even if you see changing voltage across the O2S, if it's old, replace it.

Cleaning the T-body and AIS is a good idea every once in awhile on the

3.0.

DS

Reply to
Daniel J. Stern

I can't tell for sure. I cannot find anything in the repair records of my friend for the last 7 years or 120,000 miles - so it's probably that old for sure, if not OE. I also cannot locate the sensor yet to identify if it's OE or a replacement. In the manual it looks so obvious, sitting on the exhaust manifold all by itself. Is it possibly under the air filter in the rear near the firewall & that must be removed to see it or I am just missing it?

That's good to hear. The manual says to have a Snap-On YA8875 socket which was a bit discouraging unless there's something like that I already have. Ill feel better once I locate it.

The manual says to release the pressure but is that necessary for just the throttle body? Does not seem so since fuel lines are not connected to it that I would remove? I asked the service manager at the dealership and he said don't bother with releasing pressure if not messing with fuel lines.

But releasing the pressure, if I need to, is done by removing the gas cap releases a lot. Then there's also the disconnection of the injector wiring harness (visions of ruining it by disconnecting it), then connect a jumper wire to A142 circuit terminal of fuel rail harness and the other end to 12+ volts, and another to a good ground and then to the injector terminal for 2-3 injectors. Do mechanics do all of this as says in the manual?

I gather one could clean the throttle body with just disconnecting that hose going to it. I was suprised to see Holley there, thought of the old Holley carburetors. But to get the AIS motor to clean, one would have to disconnect the throttle body? Unbolt it and so on or somehow unscrew the AIS motor?

If I get to it, I think you recommended Berryman's B12. How does that compare with the official de-carb cleaner from the dealer 4318001AB? Is it like the sensor, 1/2 the price but just as good if not better?

Hmmm, thanks, don't think this has been done in years. Now here's where I would have to release the pressure, once I find it. Looks easy in the manual.

Reply to
treeline12345

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