Fuel Trim Additve Banks 1 & 2 Low

[dedahed]

Can anyone help me understand what these codes mean - I just purchased my 99 540IA (w/ 50k) and it came with a few stored codes. thanks!

[billB]

Dedahed... to this forum

P1158= Lack of Downstream Heated Oxygen Sensor Switch - Sensor Indicates
Rich - Bank No. 2...good luck

regards
billb

[dedahed]

Thanks, billb -

The car had been sitting for quite some time (3 years with less than 1000 miles) on a dealer lot. Do you think old gas might have anything to do with it?

It does not re-code once the code was cleared.

Thanks again,

dedahed

[dedahed]

I have:

Cleaned the MAF, replaced the Air Filter, replaced the Fuel Filter, relaced the Spark Plugs, cleaned the Throttle Body, and checked for leaks downstream of the MAF - none.

I recently saw this post at http://www.bba-reman.com/content.aspx?cont...ts_and_tips_bmw

THERMOSAT SOFTWARE &OXYGEN SENSOR/MISFIRE REPROGRAMMING
MODELS AFFECTED:
E38-740I/IL with M62/M62TU produced 4/97-8/99
E39-540I/IA with M62/M62TU produced 4/97-8/99
FAULT:
The check engine light is illuminated and stored in the Engine Control Module(ECM/DME)
are one or all of the following fault codes due to a software error:
· FC 10-02 sensor pre catalyst (bank 1)
· FC 12-02 sensor post catalyst (bank 1)
· FC 18-02 sensor pre catalyst (bank 2)
· FC 20_02 sensor post catalyst(bank 2)
· Various misfire faults
CAUSE:
DME calibration software.
SOLUTION:
Check the DME program number& if necessary the DME must be reprogrammed.
Note:
When ever any of the previously listed faults are set, there is no need to replace the oxygen
sensor(s) with this programming update.

Can anyone confirm for me that this 'Tip' may in fact be the axact scenario affecting my 540IA - (My manufacture date was 1/99)?

Has anybody run into this before? If so, can someone advise how to check the DME program numbers, and also help me understand what numbers would indicate the need for the programming update? ghead

[Dirty_Tool]

I doubt if you need that reprogramming on your car but i guess it is possible. Post the last 7 digits of your vin and i can give you a more accurate description of the fault codes. Intake gasket leaks and also rear PCV plate problems are very common on this engine. need to get a better definition of the codes though before I can help.

DT

[///Matt]

I've had the same codes read out on my 540i... My end result was that the intake gaskets had cracked (yours probably have considering they've been sitting awhile) If you start getting cyliner misfires, id put money on that you're getting air in from a gasket.

[dedahed]

So I went to the stealership, told them I was willing to chip in for 1 hour of Diagnostic time... No reprogramming necessary (so they say). I was told to replace the MAF (even though it was not reading out of spec) and that they really couldn't diagnose any further until the MAF replacement was done.

They told me that it is reading both Additive and Multiplicative faults on both banks.

Instead of the $429 they wanted (part with CCA discount plus installation), I have ordered one through getcoolparts.com for just over $200 shipped. It should arrive tomorrow, and we shall see.

The last 7 of my VIN are GM62871.

So how tough is the intake manifold gasket replacement? It doesn't look like it would be that difficult - thoughts, comments? Could I test for leaks by spraying air intake cleaner around the edges of the manifold?

What are the tell tale signs of the rear PCV Plate issues that you mentioned, above? How involved is addressing this kind of issue?

[bryan1970]

you can check for intake gasket leaks with intake cleaner. but if the leak is on the inside part of the gasket that is ubder the manifold it might be difficult. the intake gaskets aren't too bad to do. the biggest thing is making sure you get everything un plugged and plugged back in to where it came from.

usually if the PCV plate is bad the car will run rough,have blue smoke come out of the back, and most of the time it will make a noise, i have herd some people describe it as a turkey call soudning noise. if you change the plate with the manifold on the engine it is a pain in the butt butif you already have the manifold off it would be best tochange it themn so you don't have to do it later on when the manifold is on the engine.

[screwdriver]

had this problem exactly on a uk spec e39 535 sport , ended up cleaning maf sensor very carefully with carb cleaner which cleared multiplicative faults ,then used fuel cleaner called protec on a very low tank which cleared additive faults [suspected dirty injector] within about 2 miles now all okay

[dedahed]

I know it has been a long time, but I thought I'd add the final resolve: Cleaning my MAF did not do the trick, but replacing it did. Thanks to all contributors for your invaluable assistance.