XSeries-forum

Could a dodgey MAF throw up this fault? I replaced the MAF when I changed the EGR valve. Still getting the following error codes:

4BB6 Air mass meter

4501 EGR deviation control

I didn't have the MAF fault prior to changing it, so going to get another one.

I pretty sure my vacuum hoses aren't blocked. Could the EGR cooler cause a problem?

Did you get an further with this ?

Leslie wrote: ↑Wed Jun 15, 2022 9:02 pm Did you get an further with this ?

No, been too busy to sort it out unfortunately!

Now getting the fault - 4501 EGR deviation control - daily now after I've driven and then turn engine back on.

4BB6 Air mass meter comes up when I boot the car, got a refund for the MAF fault with change it soon for an OEM item.

Not sure what it could be, but vacuum pump is my next replacement plan?

One interesting observation was when I used the ISTA MAF test, I did this with previous MAF (don't think anything was wrong with it) and the current after market one I've had a refund for. The observation was when it holds mid range revs for a period, later in the test cycle the exhaust starts smoking excessively. Outside the car a strong smell of unburnt diesel. would be interesting to see if this is pointing to a known fault?

Replacement actuator didn't sort problem still got following error codes:

- 4501 - Exhaust gas recirculation control, control deviation
- 4BB6 - Air Mass Meter

Got all the above plus one below one time too all though this one hasn't repeated:

- 4507 - Exhaust gas recirculation control, control deviation

The first two repeat every time the engine is turned on...

I was hoping problem would go away but hasn't so need some help please.

I've already checked vacuum hoses during actuator change, cleaned the inlet manifold and changed the MAF although I've acknowledged this new part is defo faulty by doing the INPA tests. Also changed the EGR valve, still no change.

MOT is due in the coming months so need to sort soon, emission fault will come up....HELP

Isn't it perhaps time to consult with professionals, even a main dealer?

They don't come cheap I know, but maybe they can sort this out.

Do you have black smoke out the rear when you rev it up?.....is it not a new Bosch MAF?

No black smoke, changed to a new Bosch MAF yesterday.

Just getting the following error now:

4501 Exhaust gas recirculation control deviation - Signal or value below threshold

Has anyone had similar fault relating to the pressure actuator?

Found this online:
4501 - Exhaust Gas Recirculation- Negative Deviation / Air Mass too High
This is set when the following occur:
MAF - Mass Air Flow sensor not reading correct air mass
MAP - Manifold Air Pressure not reading correct air pressure
EGR - Exhaust Gas Recirculation not working properly
The MAF sensor reads the mass of the fresh air entering the engine. It uses a temperature sensor to measure the air temperature and calculate the density of the air being sucked in. That measured air mass goes through the air filter before being compressed by the turbo-charger and passed through the intercooler and into the intake manifold.

The MAP sensor measures the pressure of the air in the intake manifold and passes the information to the DDE.
The DDE monitors both the MAF and MAP values and adjusts the fuel ratio in the injectors trying to keep about 14.7:1 ratio.
The EGR takes some of the exhaust gases coming out of the cylinders and puts it back into the intake manifold to be mixed with fresh air and reused in the combustion cycle. Introducing exhaust gases into the combustion cycle lowers the temperature of the combustion in the cylinders lowering NOX emissions.

When one of the above three systems, MAF, MAP, EGR, do not work properly you get fault code 4501 along with a "Increased Emissions" message on the iDrive, sometimes.
The MAF reading can be "calibrated" by performing a MAF adjustment and the new value can be stored in the DDE.
The MAP readings are usually corrected by replacing the MAP sensor.
The EGR system is controlled by vacuum through a pressure converter that is controlled by the DDE.
Vacuum leaks (worn vacuum hoses, defective pressure converter(s), leaking brake assist booster, worn vacuum pump, ...), a clogged EGR valve or cooler, can affect the operation of the EGR system.

As a last solution you can adjust the EGR duty cycle using ISTA-D.
This feature is available in ISTA-D (Rheingold) 4.05.31 and 4.03.31. ISTA-D 4.15 and 4.16 do not have this feature.
With ISTA-D you can adjust the amount of EGR gasses reintroduced back into the combustion cycle and the new value is stored in the DDE.

In my case the 4501 fault would appear after driving for about 15 minutes and coming to a stop. With the engine warm the EGR is active during idle, like when stopped at a stop light. Another point I noticed was 4501 would only set when outside air temperature was above 10C meaning less dense air. After a few days the error code would go out only to return the next day and again after driving more than 15 minutes (time to get the engine warm) and when coming to a stop.
I adjusted the EGR duty cycle or value with ISTA -D and 4501 has yet to return.

Thanks Marti for the advice, will give it a go.

Fitted new MAF and EGR Valve, not many more options to go!

MAP sensor replaced today, ran engine for a while, turn off, then back on:

4501 Exhaust gas recirculation control deviation - Signal or value below threshold

Spotted some oil around vacuum pump, will try changing the o-ring seal see if that works...

It wasn't the vacuum pump o-ring.

Did you ever get this sorted have a duck under the bonnet quacking away now this past couple of days can hear it when engine is off for about 30 secs Re the Egr codes maybe the Egr cooler could be blocked and not allowing any Egr flow ?

Duck quaking is the actuator under the inlet manifold, you need to take the inlet manifold off to get to it.