Hi all,

Hoping someone here can help me out. I’ve got a 2018 Ford S-Max 2.0 EcoBlue, and I'm dealing with a weird issue. There are no fault codes on the car and its running under powered, like its in limp mode
On checking the live data stream from the PCM i have these weird reading from exhaust gas sensors
 

🚨 The problem:

• Exhaust Gas Temperature Senor EGT13 ( bank 1 sensor 3 ) constantly reads 2327°F

• Exhaust Gas Temperature Senor EGT14 ( bank 1 sensor 4 ) is showing 5439°F

• Exhaust Gas Temperature Senor  EGT11 and 12 stuck at 212°F even when starting from cold

• Charge Air Cooler Temp shows -40°F

• DPF substrate inferred temp is at 14,910°F, moving down and up

• No engine light, no fault codes, but car feels underpowered ( in limp mode?)

🔧 What I’ve done:

• Replaced EGT13 with a brand-new sensor, this did nothing

• Checked voltage at the sensor plug (scan tool says its geting getting ~6.55V on egt 13)

• Unplugged the sensor EGT 13 — value stayed the same

Still no change. Battery reset didn’t help either.

 

Has anyone seen anything like this — bad sensor readings with no fault codes?

 do all these sensors share a same groundwire or something  great to hear from anyone who’s dealt with something similar. Cheers!

 

 

It is more likely to be a fault with the Code Reader than the car.

10 hours ago, Harlow said:

There are no fault codes on the car

Do not use a generic code reader to diagnose faults like these.

Use only genuine Ford main dealer equipment or FORScan.

On 4/7/2024 at 8:59 PM, unofix said:

FORScan (for use with Windows Laptop) : https://forscan.org/download.html

It's what many Ford owners use including some Ford technicians.

• vLinker FS, cable for laptop: https://www.amazon.co.uk/Vgate-vLinker-Adapter-FORScan-MS-CAN/dp/B0952P4MLP

OR

• OBDLINK EX, cable for laptop: https://www.amazon.co.uk/OBDLINK-EX-FORScan-OBD-Adapter/dp/B081VQVD3F/ref=sr_1_5

For diagnostic use only:

• vLinker FD, for android phone: https://www.amazon.co.uk/Vgate-Bluetooth-vLinker-Scanner-Diagnostic/dp/B08H82WC8L
• vLinker FD+, for iPhone: https://www.amazon.co.uk/Vgate-Bluetooth-vLinker-Scanner-Diagnostic/dp/B08H8JHWP2

 

Search Tag:   FORScan123

 

i used a topdon phoneix lite 2 , could that be a problem??

 

 

You would need to try it on another car to confirm. 

heres some more reading from a different app , this time carista evo

 

the exhaust temperatures reading are the same, but in ,C not F

why would all the exhaust   sensors but at default / extreme values??

could this be a simple fuse or relay related issue??

15 minutes ago, Harlow said:

could this be a simple fuse or relay related issue??

No.

any ideas what this could be ??

 

its strange that all 4 temperature sensors at at default or maxed out levels,

 

when you ask chatgpt to act as a master mechanic, and upload all the information, and pictures of the fuse box and fuses tables, it does pinpoint some pcm fuses inside the engine bay fuse box to check out

 

it does also say it could be a bad earth across all the sensors or maybe even a problem in the ecu itself

 

i was just really hoping i could just look at a fuses and say there it is, its blown and be a very easy simple fix

 

this is chatgpt  response to the images i upload above

🔥 Exhaust Gas Temperatures (Image 1)

Sensor	Value	Notes
EGT1 & EGT2	100°C	High for a cold engine. Likely default value or offset
EGT3 & EGT4	3004°C	🔥 Impossible. This is a classic “open circuit” or signal error

⚠️ Conclusion:
EGT3 and EGT4 are either:

• Not getting a proper ground or signal return

• Have broken wiring

• Or are sending a “fail-safe max” reading to the ECU

This will absolutely prevent regen and cause limp mode.

---

🌬️ Turbo & Intake System (Images 2–3)

Sensor	Value	Notes
Boost Pressure (actual vs. desired)	15 PSI	This is ambient pressure. No boost being created. Turbo isn’t building pressure.
VGT position	~77% (requested and actual)	Stuck nearly closed — this could be due to limp mode or default failsafe
Air Mass Value	10.55 g/s at idle	Normal at idle, but will need to check under throttle later
Accelerator Pedal	0%	Likely just idling when snapshot was taken

⚠️ Conclusion:
Your ECU is requesting and seeing no boost, keeping the VGT vanes nearly closed. This points to restricted operation — not a mechanical fault, but an ECU command likely due to sensor faults.

---

🧯 DPF System (Images 4–5)

Parameter	Value	Meaning
Last successful regen	1286.9 miles ago	🚫 Way overdue — no regen happening
Average regen interval	157.2 miles	Normal when working right
Soot load	3.3–5.38 g/L	Getting close to regen trigger (6–7 g/L is often max)
Normalized regen trigger	67.5%	Approaching threshold
Last regen duration	0 minutes	Confirms: no regen has occurred

⚠️ Conclusion:
DPF is overdue for regen, but the ECU won’t initiate it because:

• It doesn’t trust the EGT sensors

• Regen logic requires valid temp feedback

• 3004°C makes the ECU think the system is already way too hot

---

🧠 Summary of What’s Going On:

System	What’s Wrong	Effect
EGT sensors (3 & 4)	Reporting impossible temps	ECU blocks DPF regen and limits power
Turbo system	No boost being requested or delivered	ECU enforcing limp mode
DPF	Overdue regen, rising soot mass	System is waiting on correct sensor data

---

✅ What You Should Do Next:

1. Test Wiring to EGT3 and EGT4 Sensors

• Confirm voltage and ground at connector (one pin should have 5–6V)

• Do a continuity check from sensor plug to ECU pin

• If sensor is brand new and still reading 3004°C → it's almost certainly a wiring fault

2. Use FORScan If Possible

• FORScan can sometimes reset sensor learned values

• It will show if the ECU thinks those sensors are missing, open, or failed

3. Inspect Fuses Related to EGT Power Supply

• If a shared fuse for EGT power is blown, the circuit may be floating and reporting nonsense

---

 

i will try testing it on forscan , see if that produces any more infomation

heres what it said when i feed in all the fuse box pictures and tables from the user manual

 

Great — let's focus your time by listing only the most likely fuses that could explain the false EGT readings (3004°C), blocked DPF regeneration, and limp mode.

These are chosen based on:

• Their connection to the Powertrain Control Module (PCM)

• Their likelihood of powering EGT/DPF sensors or signal circuits

• Or being tapped into

---

✅ Top 6 Suspect Fuses to Test First (Highest Probability)

Fuse	Rating	Location	Label	Why It's Important
7	20A	Engine Bay (Top)	PCM Vehicle Power 1	Likely powers core sensors like EGT and MAP
8	20A	Engine Bay (Top)	PCM Vehicle Power 2	Supports additional emissions and engine sensors
11	15A	Engine Bay (Top)	PCM Vehicle Power 4	Frequently tied to exhaust sensor logic
12	15A	Engine Bay (Top)	PCM Vehicle Power 3	May power DPF temp sensors or EGT logic lines
26	10A	Engine Bay (Top)	PCM Run-Start Control	Could affect ignition-on signal to sensors
60	40A	Engine Bay (Bottom)	SCR/Exhaust Aftertreatment	High chance it’s shared with DPF/EGT system power

---

⚠️ Why These 6?

• EGT sensors 3 & 4 are almost always PCM powered.

• Your values (3004°C) are classic “open circuit” defaults, likely caused by:

  • No voltage to the sensor (blown fuse)

  • Or no signal return (broken or unpowered wiring)

• A blown fuse here could also block DPF regen logic, trigger no-boost failsafe, and cause low performance — even without a fault code.

---

Optional (If the 6 Are Fine):

Fuse	Rating	Location	Reason
21	15A	Engine Bay (Top)	Transmission control — could link to limp behavior
57	20A	Engine Bay (Bottom)	Diesel vaporizer — part of DPF system
85	20A	Engine Bay (Bottom)	Fuel fire heater — common MOD wiring tap-in point
5	20A	Passenger Compartment	Push-button ignition logic — might affect PCM boot logic
34	30A	Passenger Compartment	Run-start bus — feeds ignition signal to sensor systems
37	20A	Passenger Compartment	Voltage stability module — could affect signal reliability

---

Next Step:

Start by checking those top 6. If any are blown — you’re likely going to see that EGT3/4 drop back to realistic values straight away.

does any no the locations of Exhaust gas temperature sensors , 13 and 14, is that Bank 1 , sensor 3 , and Bank 1 sensor 4

 

on the 2.0 diesel ecoblue engine , the image from ebay of the exhaust shows the 3rd on down with a blue wire

so would that be egt 13

But should the sensors egt13 be after the dpf, and no idea about the egt14, maybe further down the exhaust system

is the first box the catalyst then the second box the dpf on these pictures? The ford parts guy mentioned something about the third sensor being after the dpf

i also found this listed on ebay as a dpf

FORD GALAXY MK4 2.0 ECOBLUE EURO 6.2 DPF FILTER 2016-2019 MT19K

would those 2 sensors potentially be egt 13 and or egt14

On 4/7/2025 at 11:21 AM, unofix said:

Do not use a generic code reader to diagnose faults like these.

Use only genuine Ford main dealer equipment or FORScan.

 

i just run forscan to see the live values and i am getting the same values on the sensors

 

 

 

1 hour ago, Harlow said:

and i am getting the same values on the sensors

Please post screen shots of the FORScan live data.

Heres a live data reading from forscan

images where screen shots from a video , thanks for looking

 

g

so i also got a print out of the exhaust sytem from the ford parts department, but the guy there could not seem to identify which  egt where  bank 1 3, and bank 1, 4 

if you look at the parts diagram from ford and compare it to the readings on forscan, could it be the fact there are no EGT sensors 1/3. 1/4 fitted???

As well as some other stray data  you see, like engine coolant sensor 2 showing -40C (on a warm day) etc

could these blank/ no existent sensors  just be being defaulted to fail safe values giving these readings and NO fault codes at all

my car is one of the very first ecoblue smax models, not sure if that makes much differance

But the other big question then is why is it in limp mode and why is there no DPF regens happening, the data states over 1000 miles since the last regen

 

 

 

 

Are there still no fault codes showing on a DTC scan with Forscan?  It shouldn't be in limp mode without any Ford specific codes.  Which potentially means it's being physically restricted by a clogged DPF for example.

12 hours ago, Harlow said:

But the other big question then is why is it in limp mode and why is there no DPF regens happening, the data states over 1000 miles since the last regen

So, the EML is not on meaning that it is not actually in limp mode, only that it is driving and behaving as if it was in limp mode.

This does sound like it is a physical issue, and as Tom has suggested there is a good probability the DPF is now blocked.

For DPF blockage only (I haven't followed the details of the other multiple issues) check DPF differential pressure values and, to a lesser extent, soot loadings open and closed circuit to check that?

No mention of testing voltages and ground continuity back to PCM that I can see, as temperature sensors of this type are usually resistance thermometers so a very high temperature implies very high resistance AFAIK?

there are no fault codes on any module on forscan, so no faults showing

I was about to check the senors voltages and ground continuity back to PCM next, does anyone no where the pcm  is located on these cars??

i will redo the live data again in forscan, and highlight the DPF differential pressure values, soot loading open/closed circuit as you said , is there anything else worth showing

 

Should i select these values in live data:

• ✅ DPF_DELTA_P

• ✅ DPF_SOOT_LOAD

• ✅ DPF_ASH_LOAD

• ✅ DPF_REGEN_STATUS

• ✅ EGT13 and EGT14

• ✅ DPF_EGT_1 or DOC_EGT

• ✅ REGEN_ATTEMPTS

• ✅ DPF_Pressure Sensor 1/2

• ✅ Engine RPM (to help compare under rev)

is it safe to do a forced regen on this car ???

 

the dpf is not easy to access on the ecoblue smax to remove it off and try to flush it threw

 

one thing to note is the previous work, if this sheds any light on what be a issue here

21/03/2024 - 87,032 -  Engine management light / Regeneration of particulate filter   - at independent garage

15/05/2024 - 88,815 - Remove and refit NOX Sensors - ford main dealer

07/08/2024 - 90,575 - remove and refit injectors (all) - ford main dealer

mileage is now 91,500

 

 

I'd check all of the live data items around the DPF (for the initial fault then move on to the others) to look for anything significant.
Personally I DON'T recommend forced regen unless absolutely necessary and with justification from the data (DPF pressure at idle and 3000 plus soot and ash loadings, secondary).
See O'Rileys on You Tube who explains a lot around this and rarely does forced regen - he uses a foam cleaner  (can get on eBay) injected into front of DPF:
https://www.youtube.com/@ORileysAutos
The extensive work done with no fault codes  (?) or any history/justification is a worry but unable to make any sense of it - very often, it's guessing without testing (at customer expense)?

2011 PCM is under passenger side wheel arch liner but they may have hidden it elsewhere?

i recently just got the car, all the work listed was before i got it, it was just on my service history printout, just postimg it to see if it might shed light on the current issue




so if your doing the foam cleaner method , with the foam and a air gun , like the guy at oriileys does all the time on his youtube

you need to go into the side of the dpf with the foam

 

like the pipe in this image

heres the reading of the live data from the dpf

 

holding revs  at around 2000 rpm

 

 

 

at idle