2009 F01 740 - Lambda Error

[markye83]

Got a CEL on my car earlier which looks odd. See below:

Engine electronics MSD 87 6 Cylinder N54 - 2 errors

118802: 0x118802 Lambda probe after catalyst, mixture control: Exhaust gas after Catalyst too lean

128301: 0x128301 Lambda probe before catalytic converter, system test: Signal constant fat

Trying to pin point the issue but can only assume one is reading wrong or both are reading incorrectly. Car is running fine aside from a cold start like idle in traffic yesterday. Is it safe to drive for a couple of days until I can get it repaired. Will it just run rich until its fixed.

Thanks!

Mark
Engine electronics MSD 87 6 Cylinder N54
2 errors
118802: 0x118802 Lambda probe after catalyst, mixture control: Exhaust gas after
Catalyst too lean
128301: 0x128301 Lambda probe before catalytic converter, system test: Signal constant fat

[dworthy]

Welcome to the Forum Mark!

How many miles do you have? Also what are you using to read the trouble codes?

I would think that you need to know which bank it is referring to as you have 4 oxygen sensor on that car, Bank 1 and 2.

[markye83]

Thanks Darin, I expect to be on here a lot.

The car has 45,000 miles. I’m reading the codes using the BimmerCode APP. Unfortunately there wasn’t a garage open yesterday afternoon so I had to take this route. The temp codes on the engine before I cleared them are below. I cleared to see if the issue came back.

6 errors
1
Page 2
12AF08: 0x12AF08 Lambda probe after catalyst, in thrust, from fat to lean:
delayed reaction
128501: 0x128501 Lambda probe before catalytic converter, in thrust: signal outside limit value
107801: 0x107801 Tuning protection: Air mass too high
213401: 0x213401 Powermanagement, undervoltage: undervoltage detected
118802: 0x118802 Lambda probe after catalyst, mixture control: Exhaust gas after
Catalyst too lean
128301: 0x128301 Lambda probe before catalytic converter, system test: Signal constant fat

My main concern is I need to use the car and won’t be able to get it repaired until Tuesday.

Thanks,

Mark

[dworthy]

It seems that whomever was paid to translate the codes did it badly. I don't know what "Fat" would translate into but I haven't seen that in a code before.

So how does the car drive? Does it seem low on power or just like normal with the SES light on?

[markye83]

Seems to drive fine but did have one period of under power yesterday during a 250 mile round trip. Original output below. I used Google Translate before. I thought fat is some kind of translation for ‘rich’.

Thanks very much for tour reply.

12AF08: 0x12AF08 Lambdasonde nach Katalysator, im Schub, von Fett nach Mager:
verzögerte Reaktion
128501: 0x128501 Lambdasonde vor Katalysator, im Schub: Signal außerhalb Grenzwert
107801: 0x107801 Tuningschutz: Luftmasse zu hoch
213401: 0x213401 Powermanagement, Unterspannung: Unterspannung erkannt
118802: 0x118802 Lambdasonde nach Katalysator, Gemischfeinregelung: Abgas nach
Katalysator zu mager
128301: 0x128301 Lambdasonde vor Katalysator, Systemprüfung: Signal konstant fett

[markye83]

Seems to drive fine. At one point yesterday it was underpowered during a 250 mile trip whilst stationary for some time in traffic on the way home. The light didn’t come on until later that night. I assumed fat meant rich. I have tried to paste the original output before I used Google Translate but it says the post has to be arrp

[dworthy]

True as "Fett" can be Fat in German, and a few other words as you translate it in a sentence.

So what I would do is clear the codes, then go for a drive. Whichever code(s) come back those would be the ones active.

Next, you will need to get a better reader as this one doesn't tell you which bank is having the problems, and that is very vague when it comes to diagnosing.

[bmwdirtracer]

I see that there's a code for "Air mass too high".....and then, there are 4 somewhat contradictory codes for O2 sensors reading flawed mixtures.

While I'd be inclined to suspect that there's something amiss with the MAF readings (aftermarket air filtration?), I would absolutely want to connect the car to ISTA (BMW's diag system), and run the test plan for these codes. There are many sensors involved in mixture control, and they are all expensive, so I think it's best to get all the information you can obtain before shotgunning parts.

[markye83]

Thanks both for your replies. Really helpful. I’ve just done 100 mikes in the car with the CEL on. Since stopping for 5 minutes and then driving a further 20 the light is now off. Very strange but no adverse affects in performance or economy at all.

I’ll take it to a BMW garage on Tuesday.

Great start to the forum! Thanks again for the answers.

Mark

[markye83]

Update to this. Car went into limp mode today so I took it to BMW. There are 3 things that came up.

120408 - charging pressure control, switch-off: pressure build-up blocked.
(Replace pressure controllers for both turbos)
130308 - VANOS, exhaust: control fault, position not reached
(Replace solenoid valve)
Oxygen Sensor before CAT, Bank 1.
(Replace O2 Sensor)

I wanted to stick with BMW parts for everything but the a Bosch O2 Sensor is around £50-70 when a BMW one is £190. Would you go with Bosch? The faults with the turbos are apparently quite common so bad luck on that front.

Thanks.

[dworthy]

Yes, I use Bosch on my cars as a direct replacement for oxygen sensors.

The N-54 likes to eat the turbos sometimes. There is an extended warranty in the U.S. because of this, but it doesn't apply to the U.K. sorry.

As for the VANOS, the solenoid can be cleaned, and that normally fixes the issue.