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Gallagher99, Senior Vehicle Technician
Category: Ford
Satisfied Customers: 3333
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I have an issue with 59 plate mondeoi tdci

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Hi i have an issue with 59 plate mondeoi
Hi there good afternoon to you
Ok what is your concern ie: lack of power &email light on
What fault code keeps returning
Regards Brian
Customer: replied 2 years ago.

Hi Brian,

the car is going straight into limp mode.

Newly fitted Dpf is blocked and will not regen. fault code P246b (conditions not correct for regeneration).

the pdf new rubber sensor pipes (Old ones had split).

does my car have a diesel vaporiser ?or what else could cause the regen to fail.

Hi there ,
Ok yes the vehicle has a fuel vapourisor fitted to the catalyst assembly upstream of the DPF
These are prone to either blocking up or shorting out and blowing the fuse
We are seeing a lot of these 2.0 tdci vapourisor seeing replaced because of unsuccessful regenerations
Did you say the DPF sensor has been replaced (has this also been tested )
Was the DPF learned values reset after the filter was replaced
Regards Brian
Customer: replied 2 years ago.

My garage fitter can't see a fuel vaporiser do all mk4 diesels have one?

ecu values were cleared . how do we test the sensor. think it works as it is saying that the pdf is blocked

Hi there
Ok not all the mk4 s have them they started appearing in late 09 so yours may not have one fitted
If it is fitted its screwed into the catalyst and is easily accessed
The reason I asked about the DPF sensor is this can cause issues where by the PCM gets its reading from the sensor and thinks it's blocked but in reality it isn't
Ok firstly I would check the readings from the DPF pressure sensor
For this you will need a digital multimeter
I would like you to test the DPF sensor reading (by back probing the wires /leave the multiplug connected (must be left connected
There is 3 wires on the sensor
Pin 1 - White/violet wire - signal out to PCM
Pin 2 -brown/white - earth
Pin 3 - yellow /Violet - 5 volt feed
Check you have the 5 volt reference between 2& 3
Check the output signal voltage between pin 1 and ground at the following
1- ignition on
2- idle
3 3000 rpm
Regards Brian
Customer: replied 2 years ago.

Hi Brian, checking the sensor. there are only two wires to the unit not 3

can you advise

Hi there ,
Do you have your registration number there
This is the correct sensor (secured at the bulkhead )
Regards Brian
Customer: replied 2 years ago.

yes 2 pipes lead to the DPF from the bulkhead sensor

And you say it only has 2 wires on the multiplug
Hi there
Did you double check this multiplug as I haven't seen any with 2 wires connected to the plug
Regards Brian
Customer: replied 2 years ago.

Hi Brian

the fitter was looking at the temp probe from the dpf which had 2 wires.

The DPF sensor has 3 wires as described. the white & violet wire has no reading on ignition on or idle.

DPF is currently off the vehicle so pipes are not connected. do we need to read with dpf fitted and sensor pipes connected?

Hi there ,
do you have the registration number so I ca. Clarify the exact wiring colours as they changed in 09/10 models
We can test the ignition on reading without pipes connected
Regards Brian
Customer: replied 2 years ago.

thanks for the quick response again.

reg is RO59AZN

Ok the wiring is as follows
Pin1 - signal out to PCM (green /orange )
Pin2 - earth (white /blue )
Pin3 - 5 volt reference feed (brown /blue )
With multiug connected to sensor
Measure the following with multimeter using pin 2 as your eArth
Ignition on at pin 3 should be 5 volts this is your reference
Check the reading at the signal out wire pin 1 with ignition on
Regards Brian
Customer: replied 2 years ago.

ok thank you.

we have 4.9 on pin 3

pin 1 showing 0.4

Hi there , thanks
Ok 0.4 is slightly low but I would know more one DPF and hoses are fitted and idle and 3000 rpm reading is given as these readings when running let us know if the DPF is actually blocked
And the only code coming back is incorrect conditions for DPF regen yes
Regards Brian
Customer: replied 2 years ago.

good morning Brian

with pdf fitted and hoese connected the readings are

1.ignition on 0.4

2. engine on idle 1.2

3 300rpm fluctuatiing 1.7-2.0 difficult to maintain a steady rpm.

please advise.



Hi ant good morning to you
Ok these readings indicate a completely blocked DPF at idle your looking for around 0.6 volts
3000rpn around 0.8 volts
As soon as it starts reading above 1.2 volts this indicates a completely blocked DPF
Have you endured everything was reset ie exhaust gas temperature sensors were reset
Also is there ANY air leaks from the intercooler hoses as this is the main cause of blocking dpfs
I suspect you are getting the condition not correct due to the blocked DPF
Gallagher99 and other Ford Specialists are ready to help you
Customer: replied 2 years ago.

Hi Brian

will check with my garage guy .

he did say that the ecu settings were all reset prior to fitting the new DPF.

will check for intercooler leaks,, any other obvious checks to make ?

thanks again. ***** with a passion same problem on a 330d few years back and removed the pdf

want to find out the cause this time.


How long has the DPF took to become blocked after fitting it
As if the learned values etc weren't reset the PCM will not carry out the correct regeneration procedures
Regards Brian
Customer: replied 2 years ago.

3-400 miles it was completely blocked.

All settings were cleared when fitted according to the instructions on the new DPF unit.

Hi there
This would indicate something is coming the filter ie stuck open EGR valve or more commonly an air leak
Regards Brian
Customer: replied 2 years ago.

Hi Brian,

just spoke with my fitter . He's a good guy very experienced. Scratching his head on this one still.

Checked for leaks and theres nothing obvious. He has opened the erg and it looks clean and functional. No codes are showing for the egr on the snap-on computer he uses.

The readings on the DPF sensor are now.

ignition on .5

idle .5

3000rpm 1.4-1.7

Showing a code of PO42d Catalyst temp sensor

Circuit high bank sensor

circuit 2 pending dtc

I guess we need to manually clean the dpf. How best to do this ? any advise would be great.

Hi there
Ok if you are showing a catalyst temp sensor fault code this will cause the incorrect condition for regen as these temperature sensors are imperative to the regeneration procedure
Your readings still indicate a blocked DPF (not as blocked as previous reading of 2.1 volts )
regards Brian
Customer: replied 2 years ago.

do i renew the catalyst sensor

Hi there good evening to you
Ok there is 2 temperature sensors on the exhaust
These sensors are NTC (negative temperature )co-efficient ) sensors
Basically the hotter the temperature the lower the voltage reading
These sensors have a 5 volt feed to one side and an earth at the other side
When the temperature rises the 5 volt starts dropping (ie:Heat the tip of the sensor with a lighter and monitor the voltage reading to see if the sensor is faulty
Regards Brian.