CODE 231 - A2 SOCKET

Mike-Halewai · Post by **Mike-Halewai** » 05 Apr 2009, 19:47

94 855T wagon - 300,000 KMS (186K miles)

I have had consistently poor fuel economy in the past few months, I've had knock sensor codes thrown and the MAF fault code thrown. Then, I did not have any codes thrown for last 4 months... until today.

2-3-1 came on and seems consistent with the actual issues that I am dealing with. And that is poor accleration under a slight load, and irregular accleration under passing conditions or hill climbing.

I have cleaned my MAF, and never had the code re-throw, the Front knock sensor has not thrown a code since November.

Can anyone provide advice on this 2-3-1 code?

Thank-you in advance?

Tapsa · Post by **Tapsa** » 06 Apr 2009, 01:07

Hi, 231 is HO2S sensor telling too rich fuel mix in partial load situation. is your mpg down?Look after MAF, fuel pressure and evap.
br Tapsa

Mike-Halewai · Post by **Mike-Halewai** » 06 Apr 2009, 09:58

Yes, the MPG have been fluctuating lately. In particular in the city, they are terrible.

On the highway, I can see an extra 200kms to a tank of gas.

IE:
in the city I'm seeing roughly 13.6 L's to 100Km's.
on the hwy I'm seeing roughly 9.4L's to 100Km's.

I'm hoping that there is someone who has dealt with this scenario and might be able to provide an extra bit of insight. If i need to replace the MAF, it's pricey and I only want to replace it if I NEED TO.

Thanks for you help Tapsa, quick question(s):

When you mention fuel pressure, is there something specific to look at, ie the fuel rail, etc?

And when you mention evap. do you mean the evaporator? I'm assuming that you can't mean the A/C system.

Post by **MadeInJapan** » 06 Apr 2009, 16:17

Have you tried cleaning your MAF with MAF cleaner or contact cleaner?

Tapsa · Post by **Tapsa** » 06 Apr 2009, 23:46

Hi, yes, you can measure the fuel pressure at the end ond of injector rail (about 3kg/cm2). Yes I mean evap but it carries many possibilities not familiar to me.
But, check all leaks in air intake and vacum part, those are often compensated by ecu adding fuel resulting in higher mix.
br Tapsa
ps. in my 850 N/A I can cause o2 dtc by removing momentarily the air inlet tube from radiator to maf

icelandic · Post by **icelandic** » 07 Apr 2009, 06:03

231 and 232 codes are also associated with vacumm leaks, and vacumm leaks cause mileage to drop. In my 850 NA I got the same problem once caused by a leak in the intake manifold gasket after having removed it to change the PCV system. It was a total mistery and a pain to locate, but once corrected, problem was solved. It is not very common to have an intake gasket leak. It is much more common to find one in the vacumm lines. If you are having the 231 code coming back immediately after clearing it and if it is being caused by a vacumm leak, it is a quite consistant one. Check that out before proceeding to more complicated things like O2 sensors and MAF.

Icelandic

Mike-Halewai · Post by **Mike-Halewai** » 07 Apr 2009, 07:35

MIJ, I have cleaned the MAF with CRC MAF cleaner. It was pretty dirty looking, came out looking very clean. I cleaned the contacts, but only with the MAF cleaner. Im not certain that contact cleaner will do much different, but i will give that a try.

Tapsa, thanks for insight, I'll check over for vacuum leaks as well as perhaps the air intake and gasket.

Icelandic, the code was cleared and has not come back, I've already put put 160km's and 2 days on the car. I did the PVC last fall and don't recollect having much issues with the gasket itself, or in it being faulty. But perhaps it is worth another change if i can't find the problem anywhere else?

Post by **MadeInJapan** » 07 Apr 2009, 15:10

If you've already cleaned the MAF with MAF cleaner, no need to use Contact cleaner on it- it won't make a difference. Search for those vacuum leaks...use carb cleaner on and around the connections to your small hoses and the intake manifold with your car idling...if you have a leak you'll get an engine surge. Possibly since you cleared the codes they won't come back- let's hope not.