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High Emissions light 525 d 56'reg

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Hi anyone assist, I have a 525 d 86k mls 56' pre LCI, it's had an impeccable service history, no dpf issues, no warning lights and all check boxes on I drive  indicating no issues. The MOT emissions very clean, however currently have high emissions light on, 



last year the high emissions light came on and the car ran lumpy, however the emissions light was on due to a faulty EGR, My BMW Indy replaced this along with the Air Mass meter, it cured the fault 


less as than a year later the high emissions light re-appeared, the car momentarily ran lumpy. The fault codes threw up EGR controller (I believe this is also known as EGR pressure controller/converter) and it threw up a number of glow plug errors. The Indy replaced the EGR controller or pressure converter and replaced all the glow plugs. The car ran fine for a day or two but then the light came on. The car still runs fine despite the light being on I don't think there no discernible performance loss. I have read other threads in other forums and ppl often associate temp stats can cause issues however interrogating the hidden menu, mine sits at 90-92 degrees and does not fluctuate even on long motorway it sits at operating temp, so there are no stat issues.


The Indy BMW diagnostics only throws up Glowplug controller error, however there is no issue with glow plugs because it starts on the button and all were replaced, also recently in Birmingham, we've had cold early morning spells and it starts on the button ???


I have also read other forum threads that sometimes the 4mm vacuum pipe from inlet manifold to EGR can deteriorate and in one case I read the pipe was not re-attached to EGR, but if this was the case would the car run normally like mine does or would there be power loss and excess smoke ??

i want to know whether glow plug controller can throw up the high emissions light? I don't want to be throwing money at something that may be unrelated. Is this fault just a glitch in the OBD/ECU is this quite common ? 


Please anyone any assistance would be much appreciated 


thanks in advance 

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Sorry for belated reply

Yes they have been checked no issues with them,


I just wanted to know if the vacuum pipe between the EGR and inlet would cause the high emissions light ? despite the car running fine, and I want to know whether  deteriorated or disconnected causes rough running (which incidentally isn't the case with mine), then I can safely isolate it to the glowplug controller -(othe fault code is coming up for the glowplug  controller) but want to know what's the correlation with high emissions light and the EML light being constantly on ?

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I think it does - I removed my EGR completely and the emissions light came on - the pressure sensor is the only thing that I can see that feeds into the brains. I tried blocking the pipe but still got the error.

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less than 5 seconds ago · #5
Thanks for reply,I'm not really a dab hand at technical jobs, the BM Indy replaced the EGR Pressure controller and glowplug (he should have just replaced the glowplug controller and the inlet to EGR vacuum hose whilst the manifold was stripped. The same Indy also replaced the MAF and EGR last year. I just want to be armed with enough info to direct him and let him know I can't be fobbed off, The EGR pressure controller was the recent job he did along with glow plugs and no sooner had completed the job and I drove out of the garage the high emissions and EML came on again (I initially went into the garage bcos this light came on, albeit when I Took the car in there was a discernible Intermittent power loss, which since the replacement of pressure controller and plugs, I'm not currently experiencing.

could it be just something as simple as the vacuum hose being off ? I'll try and get him to re-examine, also in relation to glow plug controller fault code if it was really faulty would the car start on the button as mine currently does, evening cold weather starts ???

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I got car back from RSJ Independent BMW I left it with them for the last week and half.


I had both EGR and Main thermostat which Indy supplied.( Car now warms up quickly and stays consistent at optimum temp whether pottering around town or on highway )


I also had the Glow plug controller (which I supplied) changed, which requires removal of inlet manifold, which was also decoked. Indy also removed swirl flaps changed gaskets and fitted blanks that I supplied, checked all vacuum hoses and resecured whilst refitting, ensured no leaks.

Lastly Fitted and  registered new Exide battery that I supplied, and completed final diagnostics and cleared fault codes, 


all of the above work all in for £250.

and best news is no more High emissions EML, 


I believe the high emissions light could have been triggered due to, 


a. vacuum hose potentially being insecure on EGR, that’s just a guess based on what’s was posted above, and because the Indy didn’t highlight this but may have been too preoccupied stripping it to notice. He did say the vacuum hoses  were all intact and not deteriorated. 


b. The only thing the Indy pointed out was slight leak on one of  inlet manifold gaskets, all which were replaced with swirflap blanking  kit. this could have been a possibility 


c. this is probably a stretch but the replacement battery ironing out glitches in various ecu’s. I’m sure I read some post somewhere that various  fault codes inc high  emissions light was triggered by low battery and surges in alternator charge. 


d. The replacement glowplug controller  allowing glow plugs to work properly, coupled with the replacement EGR and Thermostats ensure the car attains optimum temperature and runs leaner thus lowering the exhaust emissions. Incidentally this also satisfies all the conditions for a successful DPF Regen.  


Food for thought Prior to even rectifying the high emissions fault I still had 100k mls left on DPF status in the I drive menu. However rather than allowing the possibility of unnecessarily clogging the DPF due to faults highlighted above I thought best to get them rectified  as prevention is better than cure ! 


It would have been nice to accurately pin point the high emissions fault to one particular underlying cause but alas we are we’re at ! 




Edited by Aaron1875

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