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Megane 3 1.5 dci fap **Sorted**

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88K views 74 replies 8 participants last post by  eoptio  
E
#1 ·
hello

i have a 2010 megane 3 1.5 dci fap with just over100k miles. a few weeks ago the 'engine damage risk' warning came up, error code p242f. the local renault dealer did a full diagnostic, result fap blocked. they then performed a forced regeneration which sorted the error. Less than 50 kms later, same warning comes up, back to dealer who tried another forced regeneration but i would not work. they now say the fap needs replacing at a cost of £1800...when i asked what caused the fap to block there was no answer. the car is used for daily commutes of around 20 miles each way and the occasional longer trip on motorways.

other than replacing the fap, any advice please on what other things to check/try, not too keen to replace it without knowing the cause of blocking.


thanks
 
E
#3 ·
ok thanks, i ll have a look at that.

in the meantime i have got some more diagnostic info: error code dtc0200292, described as 'turbine downstream temperature regulation' and 1525f329, unknown. the first error does that refer to an issue with the dpf temperature sensor, preventing the dpf from regenerating? the level of soot is 57 g, with 3 failed regeneration attempts since the last forced regeneration by renault.

thanks
 
L
#5 · (Edited)
What scan tool are you using?


Cannot tell you how many MB DPFs I have ripped off the car, cleaned it manually, refitted it and the same MB dealership that wanted to condemn the DPF because it wouldn't clean up after a regen, and replace it at exorbitant cost to the owner, the next time the vehicle landed on their doorstep for a service, suddenly commented that its good to see the replacement DPF they recommended, sorted the moans on STAR the last time it was there.............. on my own STAR I have seen the DPF go from 189g soot to just 3g with a manual clean off the car (320 CDI with around 170000km) ................. and a forced regen via STAR doesn't seem able to lower that any further after having just installed the manually cleaned DPF.



So - before you get the DPF replaced know this:


If the ECU logic cannot see how to safely do a normal regen or a forced regen, then a regen is going to fail or not happen................. it depends on these items among others



1. You still need enough flow through the nearly "blocked" DPF to allow the extra heat and converted ash rubbish generated from a "regen" to be blown out the exhaust
2. You need an exhaust (excluding the DPF) to not be limiting factor ito back pressure (eg no silencer box with broken baffles hassling flow) - The ECU monitors the pressure differential across the DPF (read no associated blocked tubing and pressure sensor on the DPF, and also most importantly, a varying signal from the pressure sensor in sympathy with the engine speed and load), and uses that as well as the absolute exhaust pressure after the DPF to figure if the mechanicals involved are safe and not going to cause a possible fire.

3. Engine speed elevated off idle - typically 1500rpm +





IMO a blocked DPF is a mechanical condition/state as a result of the inability to convert and expel the accumulated soot (DPF's function in life) as harmless ash out the exhaust at the back of the vehicle
 
#6 ·
If any sensor is not working correctly then a forced Regen will fail..

As will a regen by driving the car..

Are you able to get under the car.. and get the engine under tray off, with a torch, have a look at the back of your engine, towards the exhaust manifold, not easy to see,, looking for black soot signs..


Check this first,
 
#8 ·
ours2012 said:
If any sensor is not working correctly then a forced Regen will fail..



As will a regen by driving the car..



Are you able to get under the car.. and get the engine under tray off, with a torch, have a look at the back of your engine, towards the exhaust manifold, not easy to see,, looking for black soot signs..





Check this first,
Click to expand...


I know what you’re thinking Stu[emoji1]
Good shout buddy
 
E
#9 ·
hello

had a look under the car, can't see black soot at rear of engine near exhaust manfold. found two temperature sensors, one in the exhaust just at the beginning of the dpf part and one before the turbo in the exhaust manifold. would i be right to assume 'turbine downstream temperature regulation' would refer to the sensor downstream from the turbo ie in the fap bit?
 
E
#11 ·
i am using maxiecu, and can monitor these parameters, pretty new to this though, what parameters should i check? the dpf temp sensor reading seemed to be stuck at 50, but after running the engine for 10 mins or so it seemed to go up. the turbo temp sensor was giving increasing readings. Looked at the egr valve last week, it seemed clean, no soot inside.

I have tried to take the temp sensor out of the fap, it seems pretty stuck, any suggestions as how to get it out?

I think I am going to clear the errors, run the engine and see what happens
 
E
#12 ·
i have cleared the errors, ran the engine to warm up, error did not come back, then tried two forced fap regenerations, both times the error came back (plus stop sign etc), dtc200292. stopped the regenerations. soot level in fap is 60g, would that prevent a forced regeneration? Both the exhaust temp sensors give readings in the live parameters of maxiecu, although in the fap regeneration part of maxiecu, the fap temperature sensor did not give a reading at all. Bit at a loss now re next steps. Am thinking to replace FAP and the FAP temp sensor, any suggestions?

thanks
 
L
#13 ·
Not all scanners can access all parameters and I dont know the particular one, but I would try to monitor and log all exhaust temp and pressure values.
the dpf temp sensor reading seemed to be stuck at 50
Click to expand...
C?


If so that's virtually impossible - if the DPF is flowing anything at all (engine runs so it obviously must) there should be very little temp drop/difference across the DPF - think like this - can you touch the location of the downstream temp sensor? ........... at 50C you should be able to without burning yourself. Exhaust temps should very quickly reach 200C (not touchable without burning) at idle even and easily go towards 400C+ when going down the road.


The regen request is obviously picking up on the fact that there is apparently no flow and thus pukes.


This off-course also assumes the scanner is actually reporting proper temp values. Any chance you have an IR temp gun you can point at the locations of the temp sensors around the DPF to correlate values?




The 60g soot content is basically a useless figure and should be ignored untill ALL parameters around the DPF is getting measured properly/normally ................. IN THIS CASE ..............and is a calculated value determined from the differential pressure, absolute pressure after the DPF and temperature reading the ECU is seeing around the DPF (fancy maths determined by Renault engineers - I doubt anybody has exact equation)
 
L
#15 ·
FWIW - the ScenicII manuals I have here (should be fairly universal ito the theory) are speaking of the pre and post DPF temperatures that are apparently monitored in order to trigger auto regen - both around 600C before an auto regen will get triggered.
The differential pressure (when measured properly by working pressure sensor) is an indication of the soot content - I cannot find absolute values here to quote, but I have seen up to the low several kpa order numbers for differentials on MB diesels I have had here.


This manual speaks of 45g soot requiring a manual regen to silence the moan on the dash.


So your 60g .................. yes its a value reported yet at the same time you say its mechanically clean? ........................ brings differential and absolute pressure measurements into question (did you check the sensor, tubes, connectors for cracks,breaks, blockages? ................ what Ours is suggesting there).................... see again my comment earlier re manual mechanical cleaning if you are 100% sure they are all pristine and working
 
E
#16 ·
i have had another look at the live parameters at idle, see attached samples , there is a difference between the readings of the temp sensor before the turbo and the one in the fap, it seems to be around 25c, the one in the fap reading lower (110c in the attached sample data file a) than the one before the turbo (135c). Should these figures be more similar, ie the sensor in the exhaust misreading?
 

Attachments

L
#17 · (Edited)
Ok - those temps are much more believable.


Can I suggest you keep the revs at around 1000 for say 5 minutes then take another batch of readings .................


There is a bunch of exhaust metal involved with huge thermal masses that will cause temp difference at too low a flow between those 2 sensors (losing heat to environment faster than exhaust flow can heat the metal and there is a bunch of that heat converted to pumping energy on the turbine too)............... FAP temp in theory should therefore always be lower than pre-turbo at very low flows.


First reaction? .......... if you are 100% sure all the associated plumbing and nipples/nozzles are clear then think you have a duff pressure sensor or the situation I mentioned before. Lets see with a hot flow set of hot flow values
 
E
#18 ·
thanks for quick response. attached another set of readings taken after running for 5-10 mins at 1000rpm. other than trying to take out the fap temp sensor (which would not come out) i have not tried anything else. the rubber hose for the dpf pressure sensor (there seems to be only one on the system) does not look cracked.
 

Attachments

L
#19 ·
From that there is absolutely nothing I can identify as being the culprit - perhaps I just am not familiar enough with Renaults yet and one of the founding fathers of the site will chime in to say where my logic is failing.


What you can try is this:


The 2 tubes running to the dp sensor on the FAP - plug the tubes on the exhaust/FAP side and leave the nipples on the actual pressure sensor open to atmosphere ................. now start the engine and report the differential pressure seen with the sensor open to atmosphere ............... dp should be close to 0 - if it is (and you will now probably get moaned at with a different error about non plausible pressure values but ignore), then I am afraid its back to my first suggestion
 
L
#23 ·
I have never done a Renault FAP ..............on the MBs I have done I removed the FAP from the car and with a high pressure car cleaner (Karcher etc) and while using a broad fan nozzle at about half pressure (adjust spray pattern on nozzle) clean out all the loose debris you can while trying to blow down the little tubes you can see (its going to get real dirty around you ) - first from the inlet side and then in the reverse from the outlet side, repeat till see nothing coming out - make sure you try and cover each individual tube/channel. Now block the intake side and make it water-tight. From the outlet side pour liquid engine cleaner into the FAP . Go bother the wife or a case of beer while it sits overnight. Next day again use the high pressure cleaner to mechanically clean the thing from both sides alternatively till no dirt comes out. Once happy stand it on end in the sun and go have a beer - if you think its dry refit and experience bliss.


BEFORE you do this though .................... whats the result of the dp reading with the pressure sensor open to atmosphere I asked about before and are you 100% sure all of that small diameter plumbing including the nozzles and nipples are open and unblocked with no cracks on there at all? ............... is the scanner reading close to 0?
 
E
#25 ·
not yet tried the pressure sensor. In case that turns out not to be the issue I am considering changing the dpf and the dpf temperature sensor (as that was the initial fault code). As I understand it, the ecu does need to be reset for a new dpf, does anyone know how to do this (other than visiting Renault)? My diagnostic tool can do a forced regeneration but does not seem to have an option to reset the dpf in the ecu, would a forced regeneration do this? Is there an issue driving with a new dpf without resetting the ecu?

thanks
 
L
#28 ·
I really think you need to re-read the whole thread again and understand that an error code is not an instruction to replace a specific sensor or component even if that sensor is mentioned in the error code - the error code is telling you that the ECU is detecting values on a parameter off a sensor that is not as expected .........................


The sensor itself can be faulty but often is not .................


The sensor can be ok and a horde of items affecting the sensor's readings may be causing the sensor to report funky readings.


Again - a blocked DPF/FAP, if properly identified, is a mechanical condition/state that can be fairly easily and cheaply rectified without resorting to replacing unnecessary sensors or DPF/FAP exactly as per your original enquiry
 
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