Our 91 240 has had an issue for the past few months.
I get a 212 O2 sensor code and check engine light on though the O2 sensor
is relatively new. I've check the connections at O2 sensor and AMM and cleaned AMM connectors. When it first happened a couple of months ago I seem to recall
reading about the preheat and #4 fuse so I replaced the fuse and pinched the spades together as fuse seemed to be loose. The check engine light went out and the car ran fine. A couple of days later the problem returned however.
The car will start fine and run fine for about the first minute and then gets bogged down and has no power, after another minute or two power returns and car runs completely fine from then on.
I'm due for CA smog test soon so need to take care of the issue.
Any help would be greatly appreciated.

thanks, Kirk S.

p.s. logging in as claim to be because i'm having trouble logging in.

Hiya Uncle kswan,

I trust you own a Bentley, Haynes, or Volvo green factory OEM manual?

Your recently replaced the 02 sensor? Yet you show code 2-1-2 via socket #2 for the LH-jetronic fuel injection and emissions? The Check Engine dash indicator illuminates.
- Check your 'new' 02 sensor using a multimeter to verify whether it is faulty (continuity across harness, heater wire, resistance between green wire and ground during heat-up, and so forth). You can find the procedure restated in the 700-900 FAQ and elsewhere.
- Inspect the harness for damage and ensure it is secure from the sensor along the three (or four) cable securing points.
- You may want to re-seat the connectors.
- Grounded exhaust? Doubtful cause. The bracket that secures the bell-housing to the header pipe in front of the header pipe to cat convertor flange still there? The bracket acts as a ground. A missing bracket may not impact an 02 sensor. This bracket is a necessary support to isolate the critical (and weak link) that is the header pipe output flange with the catalytic convertor input.

I suggest some extra checks as the OBD-1 diagnostic system is not foolproof, so you have it do it LH-2.2 style via the harness.

It is possible you have a faulty 02 sensor? I'll guess you have the Bosch 02 sensor for a 1991 Volvo 240? Not some hack and slash or some knockoff 02 sensor? Any damage to the sensor housing or the wires where they meet the sensor housing body?

More info on OBD codes --
http://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm

You do not indicate any other error codes. Have you run the test several times to verify you have recorded all fault codes?

Check for codes stored in the EZK-1xx ignition (and emission) control systems through socket #6 on the OBD-1 diagnostic box. The EZK ignition system monitors controls some aspects of the EGR system. Run the search for codes until you have recorded them all.

As you own a 1991 Volvo 240 in mighty California-state, your 240 may have EGR, and some symptoms you mention suggest a faulty EGR system.

Though locate and remedy the LH-Jetronic fault code 2-1-2 (faulty or missing oxygen sensor signal) before futzing with other systems (unless you have other fault codes).

Welp, I guess that does it. Post your answers back. Hope that helps.

Bigelow Earl Grey Tea Boy-eeeeeeeeeeeeeeeeeeeeeeeeee
--
Well hunnied and milked!

Bracket is fine.
It's not a hacked O2 sensor.
When my old mechanic replaced the sensor I was still get a code for O2
sensor but when I replaced the AMM the code for O2 sensor went away.
He should have known that a bad AMM could throw a code for O2 sensor.
I'll dig out the manuals and test the O2 sensor.
Wiring looks ok but I did disconnect the harness this summer when the problem appeared and reconnect and also messed with the #4 fuse and the problem went away for a little bit. Perhaps it was the harness and not the #4 fuse.
No EGR on this one as far as I know.

thanks.

Look at my image index. I have some images of my EGR equipped 1991 240.

Clue is that you have a pipe from the back of the exhaust manifold that travel behind the engine and into some works under the air intake port (manifold).

Hope that helps.

Duffed and Duffed in the mighty Pacific NW.

An update is in order on this situation.
I messed with the #4 fuse (tightened spades) and I cleaned the AMM
with AMM cleaner and cleaned the connections. Cleaned connections at O2 sensor
connector again as well.
Reset the codes and so far (it's been a couple weeks) so good. No check engine light and no stumble or loss of power when starting out. I'm leaning towards it being a dirty AMM but I guess it could have been something else. Runs great now.
Thanks for the help. Now I can at least get the emissions tested which is a whole other story. It barely passed 2 years ago with the nox being a bit high so I'm not expected a pass but maybe I'll get lucky.

thanks, kirk s.

Update.
Took car to be tested and failed with emissions way over the limit on everything.
Got a new cat (looked like the original was still on there) and they discovered the O2 sensor was damaged. After new cat and O2 sensor the car passed Ca. emissions with very low emissions.

Thanks for the suggestions and help.

Kirk S.

Well, we know that a catalytic converter was put on cars to burn up the sins of a non-clean burning engine. So, a new one HAD better help with emissions.

My question is, how did they determine the 0-2 got damaged when it is upstream or at the inlet of the converter. I myself, since I have more than one car, would want the old back to test it.

California law says you get old parts back, but the kicker is, if you ask for them "before" work starts and they know that loop hole!
I tell relatives tell them you want them. Besides you can always leave them or take them back for disposal as changing your mind is or can be a customer satisfaction guarantee.

I like keeping business honest and them knowing that help Similar to having an emissions inspector on a stool next to their licensed tool box.
It is why the law is on the books to begin with! It is hard to get laws to make merchants to do thing right thing when profit is a motive to do otherwise. Just check out PAC's and lobbyist.

Color me skeptical, but IMHO, they had you buy them an "all new parts were installed" insurance policy for their emissions work. Less sweat off their...ummm....brows!
Of course, I am going with this on the term you used as being relatively new. They are usually good for 30 to 50k miles but for sixty to eighty dollars, cheap tires last that long!

Just maybe the sensor died an early death as defective. You might take your receipt down with your two emissions reports, highlighting the sensor and get a replacement!
Electrical stuff is hard sometimes but not that hard with paper proof of before and after. Might help get some of that rip off emissions ( tax or fee, still three letters) money back!

Enough yapping! I am just an old hard liner that squeezed nickels from when they had buffaloes on them. Just in case there was more in there to come out!

Phil

Seem like you got a true blue intermittent problem but you say it is during warmup mode.

This is a crucial time during engine operation as it is continually battles temperature changes. With all the proper working components that is a no sweat deal.

Since you say it starts fine and later runs fine it tells me that the components are working DARN well. To back up, I will say DARN it!

Bogging down points to SOMETHING of the road map of the computer like improper mixture and that code is saying rich/lean.
The easiest way to get to that condition is an air leak.

There are two place that can be first suspect. Behind the AMM along that hose, any clamps or other hoses connected to it.
The next is behind the throttle body itself, the manifold hoses and the intake gasket under the intake manifold.

The reason I pick on these is because...they are shake and bake related. Shaking opens cracks and heat expands things....like cracks in gaskets...or even hoses!
I think it is just starting and will get worse until it shows its ugly head a little higher. Actually this condition is like having heads that are twisting and turning! ):( mean little devils.

Tell us a bit of history on the car. Overall condition like mileage with general notes of whether it has beaten up or not.

More Boarders will follow.
Phil

It's in good shape and hasn't been beaten up.
A couple of years ago my long time mechanic dropped the ball on a few things and incorrectly diagnosed a poor run. He changed the O2 sensor as it was throwing a code. I suspected AMM and asked him to check it but he didn't. Car ran worse when I got it back from him so I worked on it on my own, which I usually do but time didn't permit me initially. Throttle body was cleaned, IAC, plugs, wires, etc.
CA car that doesn't get much wear and tear. After doing much maintenance as such I replaced the AMM with a boneyard good one and all was fine.
I have my suspicions since fooling with the fuse a couple of times seemed to solve the issue. Perhaps the spades on the #4 fuse are not making contact well.
My new mechanic who is great but hasn't checked this issue out mentioned AMM.
I guess another trip to the boneyard could be worth it.

Kitty brought a good point about the EGR.

It will turn on the light if the valve on the fender does not pass vacuum to it.

It is a good source for the excess air I mentioned.

All his points are well stated.

He needs a thumbs up!
Phil

I messed with the #4 fuse spades again and reseated fuse and cleared the codes.
I was able to extinguish the check engine light by doing this when the problem appeared a few months ago as well.
The last time I got smogged the tech told me I was 1 point under and passed.
He said I'd need a new cat at some point but I never got around to it.
I suspect I'm overdue on that front and should probably check into getting it replaced. Doubtful it will pass CA emissions at this point.

thanks.

I am not an emissions expert but replacing the converter would depend on the type of gases let alone the amount that was coming out. Do you still have the print out? You could not have had a check engine light, right. How many miles on the car? What kind of mileages are you getting now? Are the spark plugs burning clean of oil?

Excessive air or fuel can overwhelm even a new converter. Besides your engine light is on now!

I bought a salvage title 1984 Oregon state car that had the converter gutted out unknown to me. It past the incoming Ca. smog test with 112 k at the time. I felt the engine was running great and just took it in to smog, vin, brake and lights safety inspection. The CHP dismissed the rear door damage that the insurance company totaled the car as not structural which I thought the same way.

It was way later when I had to replace a muffler I saw the honeycomb gone and it was not in the mufflers.

These engine/ fuel management systems are better than what our domestic cars come with and that is what the smog people are use to shrugging off.

IMHO, fix the light code first as the ECU knows nothing of the converters function unless it effects the flow through the engine and that dings the foot too!
Phil

Last time it was smogged the Nox and CO were high, nox within 1 point.
When that was the case on my 84 and I replaced the cat it dramatically reduced both those numbers. this is a 91 with 200k plus miles on it and I don't know if the cat has ever been replaced.
CA is stricter every year.
I've driven the car a couple of times and the check engine light hasn't come on again since resetting the codes and fooling with the #4 fuse.
It also hasn't lost power like it was after 1 minute before. I'll drive it some more and see what happens.