Getting an intermittent service engine light so I pulled the codes. 4.H64. Cleared it, went for a drive, then pulled again. 4.H64.

A search shows this means right oxygen sensor lean. However, does that mean the lean condition exists for some other (as yet unknown) reason or does it mean go buy an O2 sensor?

<edit> Also, my mileage is crappy. I'm averaging 15mpg on the highway.

 

In this case I would believe the messenger. O2 is probably coated. If the car thinks it is lean it will dump more gas and milage goes to crap. Chould be the wire too. As to wether some other thing is the culprit only thing I can think of would be an exhaust leak. It is possible to have an injector issue too. Did you go through the diagnostics in the FSM for this code?

 

I checked the wire, it's fine.

I don't have a FSM.

 

FSM = www.helminc.com As expensive as they are, you can easily waste the cost of the manual in the purchase of unneeded parts in one project. The code only names the circuit an out of parameter reading came in on, and sometimes if the reading was high or low. It is up to the repairman to diagnose, trouble shoot, and test components before throwing money at the problem. A correct diagnosis can save a lot of money on false alarms. The FSM has excellent diagnostic charts for each of the codes.

RACE ON!!!

 

Aren't O2 sensors really cheap?

I'm not arguing CFIs point by any means......I am not sure if O2s are expensive for the later years.

 

Yes, they are cheap, but the point is moot now, as I can't get the one currently in the pipe out. I'm guessing the last SOB that replaced one didn't use anti-seize.

 

You could swap the left and right sensors. Clear the code and go on a test drive. If the code changes to the left sensor you know its the sensor, if it stays on the right then its something else.

Paul

 

They usually do not come out easily even with an O2 socket. I had a muffler shop do my last one.

 

Picked up an offset socket and got the sensor changed today. On my test loop of about 30 miles the mileage went from 14.9 to 23.9, so it's success so far. Runs like a different car now, too. May go ahead and swap the other one, as I have no idea how long it's been since they were changed.

 

Glad it worked for you thanks for coming back and posting your resolution.

 

My '95 displayed a "64" code (O-2 sensor bad, right front bank) after abruptly running very rough and very rich. I dreaded replacing the O-2 sensor, and now after the job is done - rightly so! What a pain!

One reply to my earlier thread suggested switching the rear sensor with the front sensor. Well, up on the lift, that suggestion did not appear to be as easy as stated. (Thank God for the Navy auto hobby shop.) I had to remove the right exhaust/cat piece to get to the two sensors. Here's the benefit of my labors:

The pipe/cat is one piece from the manifold flange to the "S" pipe that runs back to the muffler. Heck, no problem - take it off, replace the sensors, put it back on. Right?

The car only has 47K miles. The three nuts on the flange came off OK (with copious application of PB Blaster), so did the clamp around the pipe (just like my Harley exhaust pipe clamp.) Remove the two bolts holding the springs at the crossmember, and the left exhaust/cat pipe flange bolts/nuts, and the whole assembly drops down enough that you can get the right exhaust/cat off and over to the bench. But wait! It did not drop down as planned. H-m-m-m, must be some "mystery" bolts somewhere. Cats remain HOT for a long time, trust me. And, upon further review, there ARE two mystery bolts on top of the cat, attached to the bellhousing via a bracket, and they are a pain. Can't get a wrench in there; can't get a regular socket; had to use a 15mm swiveltail with a gawdawful assembly of universals and extensions.

Anyways, I got it off and replaced BOTH sensors (Autozone Bosch OEM, $52.99.) At the same time, I replaced the fuel filter. I could not imagine trying to replace the filter while the exhaust is still on the car.

I thank my fellow Corvette enthusiasts for their input during this whole ordeal, and hope this missive can help anyone who is faced with the same problem in the future.

The only thing left to do is replace the fouled plugs, and THAT is no picnic either.

Ride Safe, Gary

 

I was going to swap the L/R to test on mine, but once I got under the car and found out what a pain the right side sensor was going to be (and also taking into consideration I have no idea of the cars service history, it has 110k miles, and the sensor was ~30 bucks), I decided to go ahead and replace it.