[Murry101]

I've been chasing an intermittent CEL for about a year (or 1,000 miles) with no success. On several occasions I have retrieved code 12223. According to Bentley the code indicates "Air-fuel mixture too lean" and recommends tightening boot clamps, checking injector o-rings, and the ELCD valve. It also references another code and the oxygen sensor.

The CEL will turn on and off during a single drive and I don't see a pattern. Sometimes the light turns on immediately. Sometimes it turns on after 20 minutes. It turns on at idle, while cruising and under boost. I have not noticed any symptoms, just the CEL. I took some O2 sensor readings thinking it might be the issue or trying to rule it out. Voltage bounced between .100V and .600V with very brief dips to .011V. When I pulled the PCV breather nipple out of the valve cover the voltage dropped to around .100V with more frequent dips to 0.011V range. When I stuffed a rag in the air intake (I tihnk this is what the webpage told me to do to create a rich fuel condition) the voltage climbed to a range of 0.600V to 0.800V. Do all of these readings sound normal? I get the feeling I have a small air leak somewhere and not a O2 sensor issue. Just looking for some ideas here.

 

[jvanabra]

There isn't much you can learn from voltages out of the O2 sensor - narrow band sensors just identify trends rather than telling you anything specific about combustion. If voltage goes up when rich and down when lean, and during normal operation bounces between relatively low and relatively high rhythmically, it's doing its job.

If you've ruled out vacuum leaks, then the two culprits are either the ECT (NTC) sensor showing the MAF (AMM) misreporting incoming air charge. Check the former with an ohmeter, and the latter... well, it can't really be checked concretely. Trying cleaning it with MAF cleaner, maybe checking output with a Tech 2, then start swapping parts.

 

[Jim Mesthene]

Check the ELCD and related hose. It's hard to find a vacuum leak there. Spraying carb cleaner won't work, the valve only opens when the ECU tells it to. See if it opens to a vacuum leak.

 

[dbmcd]

I had a CEL indicating a lean condition also. I had checked a lot of hoses and added some hose clamps that were missing. I read this post and checked my ELCD. What do you know!!! I broken hose!
I replaced the hose and erased the CEL and so far it hasn't come back on! Looks like it is fixed! Good luck to the OP, I hope you find your problem. Anyway thanks for the clues...

Sent from my SM-G965F using Tapatalk

 

[Murry101]

Check the ELCD and related hose. It's hard to find a vacuum leak there. Spraying carb cleaner won't work, the valve only opens when the ECU tells it to. See if it opens to a vacuum leak.

Thanks for the suggestion. I'm going to plead ignorance here. How can I check "if it opens to a vacuum leak?"

 

[Murry101]

After checking the ELCD valve, which is working as it should, I replace a couple of tired looking vacuum lines. Sure enough one of them had a noticeable hole (on the underside). Hard to believe I missed this one. CEL cleared and has not come back on in the 15 miles or so I have driven since the repair.

 

[jvanabra]

Vacuum hoses are key. IMO it's worth spending for silicone even with a nonturbo just to never have to deal with this problem.

 

[Murry101]

Vacuum hoses are key. IMO it's worth spending for silicone even with a nonturbo just to never have to deal with this problem.

I've been meaning to pick up some silicone vacuum hose. I think I'll go ahead and order it now...

 

[jvanabra]

Obviously you can get them anywhere, but I've found the stuff sold by Verocious to be high quality and reasonably priced:

Verocious Motorsports – Race Quality Fabrication Parts

Universal fabrication components for custom exhaust, intake, turbocharger, and fuel systems.

www.verociousmotorsports.com

 

[Murry101]

Update: CEL has come back a couple of times, but now clears within seconds. I must have another damaged vacuum line. I have some silicone hose on order and will replace all the lines I can when I get it.

 

[jvanabra]

Don't overlook the rubber grommets in the intake manifold. There are three of them, and they can leak too. Also, though less likely, the rubber caps on the 2 (?) throttle body vacuum ports. I usually zip tie them on just to be sure.

 

[kgrosso]

I've been chasing an intermittent CEL for about a year (or 1,000 miles) with no success. On several occasions I have retrieved code 12223. According to Bentley the code indicates "Air-fuel mixture too lean" and recommends tightening boot clamps, checking injector o-rings, and the ELCD valve. It also references another code and the oxygen sensor.

The CEL will turn on and off during a single drive and I don't see a pattern. Sometimes the light turns on immediately. Sometimes it turns on after 20 minutes. It turns on at idle, while cruising and under boost. I have not noticed any symptoms, just the CEL. I took some O2 sensor readings thinking it might be the issue or trying to rule it out. Voltage bounced between .100V and .600V with very brief dips to .011V. When I pulled the PCV breather nipple out of the valve cover the voltage dropped to around .100V with more frequent dips to 0.011V range. When I stuffed a rag in the air intake (I tihnk this is what the webpage told me to do to create a rich fuel condition) the voltage climbed to a range of 0.600V to 0.800V. Do all of these readings sound normal? I get the feeling I have a small air leak somewhere and not a O2 sensor issue. Just looking for some ideas here.

Make sure that your exhaust system isn't backing up; clogging enough to trick the O2 sensor into flagging a fault. My '93 900s did that, except the light would stay lit. The previous two sentences sum up too many months of unrequited labor, parts, head-scratching and heartache, trying to suss out what was causing that light to give me the raspberry, every time I took it up Eagle Rock Ave with a wide-open throttle.

 

[Murry101]

A new development. Not sure if it is related, but I noticed that under hard acceleration the engine stumbles a little bit. Typically in the 3500-4000 rpm range. I don’t typically drive this car hard. There’s no point in doing that. Probably why it took this long to see this issue. Time to check the fuel system?

 

[kgrosso]

A new development. Not sure if it is related, but I noticed that under hard acceleration the engine stumbles a little bit. Typically in the 3500-4000 rpm range. I don’t typically drive this car hard. There’s no point in doing that. Probably why it took this long to see this issue. Time to check the fuel system?

Maybe time to check how free your exhaust is flowing. If it backs up behind those high rev's, it could be your O2 sensor, signalling the fault.

 

[Murry101]

Maybe time to check how free your exhaust is flowing. If it backs up behind those high rev's, it could be your O2 sensor, signalling the fault.

Thanks. Stumble and fault not connected. I drove it for a good 45 minutes today after replacing the intake bushings/grommets no CEL, repeated hesitation at about 3700 rpm

 

[kgrosso]

Your welcome. Exhaust back pressure is an easy problem to overlook.

 

[Jim Mesthene]

Worn spark plugs can do that.
Brand new Champion plugs can do it right out of the box!

 

[Murry101]

I replaced the plugs,wires, cap & rotor when I bought the car, so about 3k miles ago/3 years. NKG, Bougicord & Bosch. Replacing plugs is cheap and easy enough to do again as a trial. Last time I did get the non resistance plugs. Can't remember if they were 6s or 7s. What would you recommend for NH driving in the summer?

Pretty sure the wires were for a different 900 as the numbers (for cylinder) and length did not match what was on the car and the wire that went from the coil to the cap was a lot longer...As I recall the 1 and 4 cord lengths were transposed.

 

[Jim Mesthene]

I used to use NGK 6s for Turbos

Now, I only use one plug on my own car.

 

[kgrosso]

Worn spark plugs can do that.
Brand new Champion plugs can do it right out of the box!

Champion;...ugh...lawn mower plugs. On the other hand, you can run NGK's so long that you'll forget when you bought 'em; especially the platinum ones.