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Discussion Starter #1
Over the past month or so, I have noted that my 56 plate 159 1.9 diesel (just under 80k) has been a little bit unresponsive in lower revs. Fine when the foot is to the floor and nothing particularly different about the mpg.

I've been monitoring it closely, giving it a good boot around on the way to force any dirt out the back end.

At the weekend, I noticed the idle revs bouncing up and down. Not violently, but certainly more than normal.

Yesterday, I jumped in the car (with the temperature reading at over 35C!) and started up. Within about a minute, the engine management light came on. I called into a local indie garage on the way home and they hooked up the computer.

The read out gave a single error code:

P2453 - Differential Pressure Sensor Signal

A little bit of searching around lead me to believe this is an issue with:

a) the sensor itself

or

b) the rubber cable running from the DPF to the sensor

or

c) the DPF itself

or D) something else that I haven't considered.

I've jacked the car up and had a good poke around - the rubber cable appears in very decent nick and the electrical connection also seems fine. No obvious external damage to the exhaust system.

I took the car out for a good hour tonight, blasting up the A1, keeping 3,000 rpm + for the majority of the journey, but it didn't seem to enter a regen mode at all (the mpg was surprisingly good considering I was sitting at 70mph in third...). Will a DPF regen be prevented while the engine management light is on?


I suppose my main question is what is likely to be the issue, and what would you recommend? Would a DPF removal and remap be the best solution? Can anyone recommend someone who can do this in the north east?

Cheers
 

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With the EGR bypassed, physically or electronically? The later doesn't mean it is not open.
Check the MAP and MAF
 

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When I was checking EGR operation with FES I noticed it takes time for it to close after some revs. It does not immediately brings it back to values on idle. i replaced EGR around 7k miles ago and have restrictive gaskets on both sides. Car seems to work fine. Is this bahaviour normal?
 

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FES does not measure the EGR directly (it can't), it can only measure the pressure in the Manifold with the MAP, and compares that the the MAF (and works out the exected air flow).
Not measured one myself, so can't tell if it is normal. The only time the EGR really should be shut is when you demand lots of power. At all other times it tends to be open (driving on the motorway for example)
Hence why you really notice it when you put your foot down.

This is the usually programmed beahviour.

 

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Discussion Starter #7
Thanks for the replies.

Over the last 24 hours, I've removed, cleaned and refitted the MAP sensor (it was pretty dirty).

Also removed, cleaned and refitted the EGR valve. There was a slight build up of soot, but not enough to block significant airflow (it was replaced under warranty 3 years ago).

The engine management light remains firmly on. Even worse, the car now drives relatively normally for about 2-3 minutes, then falls into limp mode. Restarting the engine allows another burst of "normal driving", but limp mode returns after 30 seconds or so.

I'm confident that nothing has gone wrong with the cleaning and refitting process (it's fairly straightforward to be honest).

Might be time for the local indy to have a look at it. Might be time to cycle to work!
 

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If you cant get it regening, the garage should be able to force a regen and get it sorted, might be worth using a can of Wurth DPF cleaner at the same time.

The work you have done cleaning is not wasted, and will still benefit the car ( and shows what the EGR is pumping through the manifold!).
 

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Discussion Starter #9
Fully agree - I was happy to clean it up as it seemed like good housekeeping regardless!

Does it sound like it's a trademark DPF regeneration issue?

Would a significant build up within the DPF prevent it from regenerating, even with the hour I spend out blasting up and down the A1 in third gear?

Also, do you think it's possible that the now clean MAP sensor and EGR valve has messed with the ECU to the point where it's confused with such a sudden change? Would disconnecting the battery for an hour reset the ECU and give me a "fresh" learning sequence?
 

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Just did a search for your error code on here, a couple of threads, in both the guys reckon the rubber hose on their DPF has crumbled.... If this is the case a cheap fix.
http://www.alfaowner.com/Forum/showthread.php?t=326760


As for cleaning, should not be too much for the ECU, mine leant to add less fuel ( to reduce boost) within a couple of drives after I blanked it.

Sent from AutoGuide.com Free App
 

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Discussion Starter #11
Sorry, forgot to mention the hose from the DPF was one of the first things I checked. All seems fine.

I have unplugged the battery and will see if a reset ECU helps. I'll give it a spin in the morning.
 

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FES does not measure the EGR directly (it can't), it can only measure the pressure in the Manifold with the MAP, and compares that the the MAF (and works out the exected air flow).
Not measured one myself, so can't tell if it is normal. The only time the EGR really should be shut is when you demand lots of power. At all other times it tends to be open (driving on the motorway for example)
Hence why you really notice it when you put your foot down.

This is the usually programmed beahviour.

Thanks for the information, giblets.
 

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I had a similar issue where my 159 2.4 would just refused do its own regen, with the ecu light on and limp mode activated I checked the error with fes, only error was dpf full.

I checked the oil degredation was on 55%, and the dpf clogging was on 94%. I drove 110 miles on the motorway with it in limp mode and the motor refused to regen on its own. (i monitored through FES - filter temperature)

Got back home, changed the oil and reset the oil degradation in fes, took her back out and within the first 10 miles she did her regen.:thumbs:

Also make sure she has more than half a tank of fuel to be on the safe side (i see it mentioned a lot on the forums)
 

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Discussion Starter #14
Left the battery unplugged overnight to reset ECU.

Started it this morning and left it to idle for 10 minutes. Turned off and came back 20 minutes later to take it for a spin. Limp mode within 3.

Also tried unplugging MAF sensor but this too sends it into limp mode.

Fun times!
 
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