29f4 ошибка бмв n52

Getting codes 29F4 29F5 — O2 or Cats?

82k miles. If it was the O2 sensors, which ones would be most likely to fail? Pre or post cat?

thanks for the help.

Originally Posted by bmwdirtracer

How many miles on your car? Catalysts have an 80,000 mile warranty.

That said, if the O2 sensors are reading incorrectly, OR if you have crankcase ventilation problems, or other issues which are causing the engine to run less than perfectly, that will certainly cause catalyst efficiency codes.

I changed the the spark plugs, air filter, cabin air filter, less than 200 miles ago. Bought a scanner, cleared the codes, drove it. After about 45 mins of driving SES light came back on. I planned on changing the O2 sensors, but didn�t want to waste the money if I was going to have to replace the cats. Car drives fine, but like I said, a mild stumble from a stop.

Originally Posted by bmwdirtracer

What maintenance have you done on the car? How old are the spark plugs? What repairs have you had to do?

Sounds like you�re saying you think the cats are done, and I shouldn�t bother with changing the O2 sensors, right?

Originally Posted by bmwdirtracer

Even if you end up having to replace the cats, it would be silly to put the old O2 sensors in the new exhaust. Cats don’t just «die». Something kills them, like an engine that’s running too rich or too lean, or dumping oil into the exhaust, etc. If the cats are dead, so are the sensors.

Last edited by bmwdirtracer; 07-26-2018 at 07:30 PM.

Ok I understand. Should I replace all 4 sensors or are the 2 pre-cat sensors or the 2 post-cat sensors more likely to cause this problem?

Originally Posted by bmwdirtracer

No, that’s exactly the opposite of what I said. Replace the sensors first, clear the codes, and see if they come back. If they do, you need cats also.

But know that the cats didn’t die because they were old. If they’re dead, something killed them and you need to fix that something before replacing the cats, or you’ll just kill the new ones.

You might also want to have the latest software loaded into your car’s computers, in case there’s an update relating to this.

O2 sensors and cats are probably quite OK, since both banks are reporting the error simultaneously.

I am having the same problem on an N52B25 in a 525xi (Europe model). So far, I have eliminated other error codes that might have been causing the cat errors, including Vanos solenoid exchange and both DISA valves renewed, new sparkplugs and airfilter.

Due to excessive oil consumption, I even had a major engine overhaul done with new piston rings and crankcase ventilation and a total overhaul of the cylinder head and valves. It seemed to cure the oil consumption but had nothing to do with the cat error codes.

“My” BMW expert mechanic has found the brake booster is leaking air. And that air — he explains — ends up in the intake via the crankcase ventilation. And the electronics cannot measure that air and thus it gives the wrong air / fuel mix, which in turn may be causing the cat error codes.

And he is right that it leaks air: For about 20 seconds after I stop the engine, I can hear a hissing sound and after that there is no pressure left to assist me in applying the brakes. And if I push the brake pedal while stopping the engine, the hissing sound is delayed until I release the brake. I.e. the valve in the brake booster closest to the brake pedal is leaking air.

I hope he is right about this vacuum leak causing the cat error codes. He also claims that failing cats on an N52 is not a common problem. But the error codes are. And they are usually caused by a fault in either the intake system or the fuel injection.

I have ordered a new brake booster.

JimmyJam83: What did you do to solve your problem?

Some body needs to do the correct diagnostics before changing any parts

New brake booster mounted. It made no change to the error codes. But the brake booster is now working as it should. So no money wasted, but still left with catalyzer errors.

Next up is examining the internals of the cats with a camera.

That is absolutely correct. The camera revealed ruined catalyzers. They have now been replaced and the error codes are gone. Or at least there are no error codes after 600 km.

I am just mad that when I bought the car, I asked BMW how much oil such and engine may consume. Their answer was one liter for every 1000 km. And at that time, the car “only” consumed a liter for every 3500 km. So I was left with no possibilities for complaining where I bought the car, even though I bought the thing with 3 months guarantee.

After a couple of years and 40.000 km more, the oil consumption had worsened and was a liter for every 1500 or 2000 km. I.e. never as bad as BMW’s “specification” for what makes a bad engine. But obviously more than enough to destroy the catalyzers.

If the cat codes are efficiency faults then cats are done or you install this spark plug adaptors on the o2 sensors to pull the sensor out of the exhaust stream and the faults might not return. Of course the cats would still be bad but the light would be off.

Hi all sorry to be a pain
I have a BMW 1 series 2009 116i which kept cutting out when driving happened once 6 month ago and then recently started again and jumping when driving. Long story short I took it to a garage who did a diagnosis and the codes were:

2A26/Present — DME catalyst converter in stratified charge mode.
29F4/Not present — DME catalyst converter Conversion
23C1/Not present — Oxygen sensor emissions control.

The garage said a new converter is needed which is fine … estimated a few hundred pounds. I decided to save some money and fix it myself(the garage arent very reliable and I can’t drive it far as its stuck on limp mode) however there are TWO catalyst converters on the car (manifold and the exhaust) the garage haven’t told me which.

I’ve search google/YouTube etc. Any ideas?

Currently have a manny cat on hold at a party dealer so I have to get sorted soon! Any help or ideas would be really appreciated!

Thanks in advance!!

Originally Posted by Crpb1027

Hi all sorry to be a pain
I have a BMW 1 series 2009 116i which kept cutting out when driving happened once 6 month ago and then recently started again and jumping when driving. Long story short I took it to a garage who did a diagnosis and the codes were:

2A26/Present — DME catalyst converter in stratified charge mode.
29F4/Not present — DME catalyst converter Conversion
23C1/Not present — Oxygen sensor emissions control.

The garage said a new converter is needed which is fine … estimated a few hundred pounds. I decided to save some money and fix it myself(the garage arent very reliable and I can’t drive it far as its stuck on limp mode) however there are TWO catalyst converters on the car (manifold and the exhaust) the garage haven’t told me which.

I’ve search google/YouTube etc. Any ideas?

Currently have a manny cat on hold at a party dealer so I have to get sorted soon! Any help or ideas would be really appreciated!

Thanks in advance!!

Hey i have the exact codes well 2 of them 2a26 and 29f4… i have changed the o2 sensors but it didnt work.. did you fix your if so which catalytic converter was it the manifold or rear one and did it work after replacing ?