EGR error codes P040D00 & P040C00 (temp. sensor)

[xcelrec]

Hey!

First post here, was mainly reading until now. Roughly two weeks back I finally got a T6 transporter (CXHA) with 150k on the clock. The van mostly stood still other than the drive back from the dealer (~120km), since I'm preparing it for the conversion. Yesterday on a short drive the engine management light came on. Looked at it with VCDS and had mainly the two errors P040D00 and P040C00, which are EGR temperature sensor 1 having a short circuit to plus and minus.

These seem to be infrequent errors, but the frequency at which they occurred (shorting to +, 26 times and shorting to - 2 times) tripped the engine light. Weirdly in the VW documents, the EGR only has 'temp. sensor 2' and 'temp. sensor 3'. Whatever I thought, probably a loose connection. Checked the wires of the sensors (sensor 2 is on top of the egr cooler and sensor 3 at the side of the egr valve), they seemed fine, so I deleted the error codes afterwards.

Went for a test drive, same errors are occurring. Short to + happened twice and short to - happened 9 times. Does this mean the temp. sensor is fried or can there also be other issues? Would really appreciate if someone can shed some light on this. What also kind of bothers me, since I'm not a mechanic, can I continue driving like this or should I seek out a shop asap?

Edit: If this should've gone into 'Engine, Gearbox, Exhaust, Drivetrain' section sorry for that, please move the post if it's the case.

cheers

 

[mmi]

Looked at it with VCDS and had mainly the two errors P040D00 and P040C00, which are EGR temperature sensor 1 having a short circuit to plus and minus.

Please post unedited VCDS Auto-Scan - with the faults.

 

[xcelrec]

Please post unedited VCDS Auto-Scan - with the faults.

Hey sure, the original scan is in german tho, threw the interesting parts about the faults into deepL, hope they still make sense. I also attached the og. scan in german.

Thursday, 31,August,2023,12:23:40:59002
VCDS -- Windows-based VAG/VAS emulator runs on Windows 10 x64
VCDS Version: PCI 23.3.1.0 HEX-V2 CB: 0.4631.5
Data status: 20230627 DS346.2
www.vcdspro.de


Vehicle ID: WV1ZZZ7HZJX031893 Vehicle registration number:
Mileage: 151900km Repair order:



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Vehicle type: 7H-VN75 (7E0)
Scan: 01 03 04 08 09 10 15 17 19 25 5F 61 0B

Vehicle ID: WV1ZZZ7HZJXXXXX Mileage: 151900km

01-Engine electronics -- Status: Error 0010
03-Brake electronics -- Status: ok 0000
04-Steering angle sensor -- Status: i.O. 0000
08-Air-conditioning/heating el. -- Status: o.k. 0000
09-Central electric -- Status: i.O. 0000
10-Parking aid 2 -- Status: ok 0000
15-Airbag -- Status: ok 0000
17-Switch panel insert -- Status: i.O. 0000
19-Diagnostic interface -- Status: i.O. 0000
25-Auto immobilizer -- Status: o.k. 0000
5F-Inform. sec. I -- Status: ok 0000
61-Battery control -- Status: ok 0000
-------------------------------------------------------------------------------
Address 01: Motor electronics (2D2D2-CXHA) Label file:. DRV\04L-907-309-V2.clb
   Part number SW: 04L 906 056 KL HW: 04L 907 445
   Component: R4 2.0l TDI H02 6166
   Revision: 23002001
   Codierung: 00194014432401090000
   Operating no.: WSC 35110 790 50316
   ASAM data set: EV_ECM20TDI03004L906056KL 004012
   ROD: EV_ECM20TDI03004L906056KA.rod
   VCID: 015B48F2D1876DA2005-8054
   VINID: 9E606AAAA1D8A9AA000C12090C1EDAACF3

2 error codes found:
23786 - temperature sensor 1 for exhaust gas recirculation
          P040D 00 [096] - Short circuit on positive side
          Sporadic - unconfirmed - checked since last clearing.
             Ambient conditions:
                    Error status: 00000001
                    Error priority: 2
                    Error frequency: 1
                    Mileage: 151870 km
                    Date: 2060.01.02
                    Time: 18:04:52

                    Engine speed: 912.50 /min
                    Normalized load value: 14.5
                    Vehicle speed: 0 km/h
                    Coolant temperature: 21 °C
                    Intake air temperature: 0 °C
                    Ambient air pressure: 990 mbar
                    Voltage terminal 30: 11.453 V
                    Loss counter according to OBD: 40
                    Exhaust gas recirculation temp. sensor 1 bank 1: Raw value: -50.0 °C
                    Coolant temperature at engine output: calculated: 21.0 °C
                    Particle filter input: Temp. sensor 1 Bank 1: Raw value: 16.0 °C
                    Turbocharger 1 Turbine output: Temp. sensor 1 Bank 1: Raw value: 17.5 °C
                    Outdoor temp. sensor 1 bank 1: Raw value: 21.5 °C
                    Turbocharger 1 Turbine input: Temp. sensor 1 Bank 1: Raw value: 75.0 °C
                    Particle filter output: Temp. sensor 1 bank 1: Raw value: 15.0 °C
                    Intercooler output: Temp. sensor 1 Bank 1: Raw value: 22.2 °C
                    Turbocharger 1 compressor output: temp. sensor 1 bank 1: raw value: 23.0 °C

25853 - Exhaust gas recirculation temperature sensor 1
          P040C 00 [100] - Short circuit to ground
          Sporadic - unconfirmed - checked since last clearing.
             Ambient conditions:
                    Error status: 00000001
                    Error priority: 2
                    Fault frequency: 9
                    Mileage: 151870 km
                    Date: 2060.01.02
                    Time: 18:04:56

                    Engine speed: 823.00 /min
                    Normalized load value: 42.0
                    Vehicle speed: 0 km/h
                    Coolant temperature: 22 °C
                    Intake air temperature: 0 °C
                    Ambient air pressure: 990 mbar
                    Voltage terminal 30: 13.648 V
                    Loss counter according to OBD: 40
                    Air mass meter 1 bank 1 Air mass: Raw value: 432.7 mg/stroke
                    Exhaust gas recirculation valve 1 bank 1: Bearing return - set point: 23.00 %.
                    Exhaust gas recirculation valve 1 bank 1: Bearing recirc. - actual value: 23.15 %
                    Exhaust gas recirculation valve 1 Bank 1: Position recirc. - Offset closed: 0.00 %
                    Exhaust gas recirculation valve 1 bank 1: Position rec. - raw spg.: 2.774 V
                    Exhaust gas recirculation valve 1 bank 1: gel. Stop cooling mode: 2.331 V
                    Exhaust gas recirculation valve 1 bank 1: yellow stop. Bypass stop: 2.658 V

Readiness: Not available

In 3rd and 4th gear I also have some stuttering around 1200-1500rpm. Almost feels like the car is jumping.

Cheers!

 

[xcelrec]

Some additional information, what I noticed is that these errors mostly happen on engine start, so I logged the EGR temp. sensor 1. I cannot really see when I turned the engine on, but with ignition on the temp. was sitting at -50C, then after turning the engine on for like 10-15sec the sensor was still showing -50C and then suddenly jumped up to 40C. Is this normal behaviour? Tbh. not even sure If I logged the correct sensor.

 

[mmi]

the original scan is in german tho

Thanks, no problem there
Actually I have noticed that even in VCDS sometimes something is lost in translation and German description makes more sense. However, not sure which one is correct for these.

English VCDS:​

P040C 00 - EGR Temperature Sensor 1 - Signal too Low​

P040D 00 - EGR Temperature Sensor 1 - Signal too High​

​

German OBDeleven​

P040C 00 - Temp.-fühler für Abgasrückführung - Signal zu klein​

P040D 00 - Temp.-fühler für Abgasrückführung - Signal zu groß​

​

A short to plus or short to ground would suggest wiring fault. Anyways, something is wrong with a temperature readings.

Weirdly in the VW documents, the EGR only has 'temp. sensor 2' and 'temp. sensor 3'.

Yes, that's correct. Thus not sure if the code means the first of the sensors, or possibly exhaust gas sensor 1 which effectively would be almost in the same position as EGR sensor 1.

Anyways, there seems to be some strange values logged in the scan - it's not that cold over there??

Intake air temperature: 0 °C​

Exhaust gas recirculation temp. sensor 1 bank 1: Raw value: -50.0 °C​

​

Could you please make engine blockmap file - this might give us clues which values to look more closely.

VCDS > Applications > Controller Channel Map​

[Single Controller Address - 01]​

[Measuring Values]​

[CSV file]​

The result file blockmap-01-... will be in folder C:\Ross-Tech\VCDS\Logs\...​

PS. You can install also English VCDS - it won't interfere with German VCDS

---

Some additional information, what I noticed is that these errors mostly happen on engine start, so I logged the EGR temp. sensor 1. I cannot really see when I turned the engine on, but with ignition on the temp. was sitting at -50C, then after turning the engine on for like 10-15sec the sensor was still showing -50C and then suddenly jumped up to 40C. Is this normal behaviour? Tbh. not even sure If I logged the correct sensor.

View attachment 211757

Well, while I was typing the above it seems you have found the culprit. In the log you can see that sensors raw output is stuck at 5 Volts (reading -50C) - a common reference voltage to all sensors.

I would check the wiring first.

 

[mmi]

Please look into "Loc. IDE04035 - Temperatur der Abgasrückführung" in your log - the temperatures of sensors 11 and 12.

EGRTemp 11/12: 110/-40 °C​

EGRTemp 11/12: 110/-40 °C​

EGRTemp 11/12: 110/-40 °C​

EGRTemp 11/12: 110/-36 °C​

EGRTemp 11/12: 110/25 °C​

EGRTemp 11/12: 110/34 °C​

EGRTemp 11/12: 110/41 °C​

​

The trouble sensor/wiring is the "last" sensor along the exhaust flow.

 

[xcelrec]

Wow, didn't expect that! Thanks for the reply . I'm still quite new to VCDS and even working on cars myself, will def. install the english version for scans in the future.
If you don't mind me asking, will the blockmap include more sensor values? And can I get these after the fact, or do I need to re-record? I simply went into the engine electronics -> advanced measurement values and searched for the egr temp sensor that read -50C.

If I understood correctly Loc. IDE04035 shows both sensors together and thats also why I cannot graph them out?

Since there are only the two sensors present in the egr for CXHA engines, I assume you are talking about the one which is labeled 11 in the below drawing? I thought it was 21 on the egr cooler, since the it was labeled as "Temperaturfühler 1", so the first in the chain.

Edit: Regarding the air intake temperature - yea no, we had ~21C this evening I assume this reading comes from a different sensor, might there be some other things faulty besides the egr temp. sensor?

Thanks!

 

[mmi]

I believe the offending sensor is "21" in the picture - cooled exhaust gases - as seen in the log snippet above.

For the air intake temperature I would check:
IDE08064 Mass airflow sensor 1 bank 1 temperature sensor: raw value

Note: after driving & engine stopped might get fairly high (=normal) because of engine heat.

If you don't mind me asking, will the blockmap include more sensor values? And can I get these after the fact, or do I need to re-record? I

Yes, the blockmap file will contain everything that's available through diagnostics.
Yes, it's a different procedure to make the blockmap file - under VCDS > Applications > Controller Channel Map

PS. Would appreciate if you could make blockmaps with German VCDS (and possibly later also with English VCDS) - just would like to verify the namings as they originally are actually in German.

 

[xcelrec]

Ah yea that makes more sense, wasn't sure what you meant with "last" sensor in the exhaust chain. I've also spoken to the dealer in the meanwhile. He basically said that he hopes its only the temp. sensor and not the whole EGR. Regardless, since I bought the car including a used car warranty, a proper repair shop needs to do the repair. Also said that I shouldn't drive the car anymore, unless its to the mechanic.

@mmi For the blockmaps, ignition on is enough or should I start the engine?

Cheers for the help so far!

 

[mmi]

@mmi For the blockmaps, ignition on is enough or should I start the engine?

Ignition on is enough.

 

[xcelrec]

Ignition on is enough.

German/English blockmaps . Crazy how much information is in there, roughly 1400 entries.
EGR temp. sensor showing -40C again and intake air temp. seems normal at 18C.

Gonna try to get an appointment somewhere asap on monday. Some shops are booked out for like 3 weeks already here.

 

[mmi]

Thank you very much for the German blockmap - very helpful!

E.g. in English
IDE11872 Exh.gas temp.sen upstream of HD exh.gas recir.valve:raw val.

In German
IDE11872 Abgastemperatursensor vor HD-AGR-Ventil: Rohwert
makes more sense, especially the HD, obvious now - Hochdruck

---

By the way, probably noticed the -40°C/-50°C reported by a sensor.

IDE04035 exh.gas recirc. temperature EGRTemp 11/12: 17/-40 °C / EGRTemp 21/22:---/--- °C

IDE11872 Exh.gas temp.sen upstream of HD exh.gas recir.valve:raw val. 17.2 °C
IDE07729 EGR temp. sensor 1: B1: raw value -50 °C

The IDE04035 is a "duplicate" of the indidual sensor. Possibly just a common OBD-data channel. The values in IDE04035 are 8-bit values - thus the range is only -40...215 °C.

 

[xcelrec]

No worries man. Tbh. I'm a bit confused by the descriptions even with the german blockmap. IDE11872 seems pretty clearly descriped as the sensor before the egr valve (11 in above drawing). Why they wouldn't also name the sensor 21 (in drawing) something like "Abgastemperatursensor auf AGR-Kühler" / "Exh.gas temp.sen on exh.gas recir. cooler" is beyond me.

So we are pretty sure that IDE07729 is the culprit, right? Maybe I can save the mechanics a bit of time then. Gotta find the part number now .

Regarding IDE04035 values only being 8bit ints is interesting, do you know what kind of precision the 'normal' values like IDE11872/IDE07729 use? 32/16 bit floats?

Btw. thanks for the guides in your signature, will def. read some of them!

 

[mmi]

Regarding IDE04035 values only being 8bit ints is interesting, do you know what kind of precision the 'normal' values like IDE11872/IDE07729 use? 32/16 bit floats?

I think (many of) the 8-bit values come from OBDII-standard requirements for all vehicles.

IDE11872/IDE07729

Specifically these are coded as signed 16-bit integer values - dividing the value by 10 gives temperature in °C. Though not sure about the value -50 °C. in binary - probably the ECU decided to cut it off.

So we are pretty sure that IDE07729 is the culprit, right? Maybe I can save the mechanics a bit of time then. Gotta find the part number now .

Checking the wiring first might pay off. You could monitor the reading while twiddling the wiring harness.
On unplugged connector on ECU side you should see +5V in pin 2 (red) and solid ground on pin 1. Yes, the access to the connector is a bit tight.
Also worth checking fault codes (frequency) before and after unpluggung the connector.

 

[xcelrec]

Specifically these are coded as signed 16-bit integer values - dividing the value gives temperature in °C. Though not sure about the value -50 °C. in binary - probably the ECU decided to cut it off.

Ahhh, ok. Definitely interesting! I have a software background, but usually I'm not dealing with a lot of low level stuff.

Thanks for the part number as well! Don't think I will get around to measuring at the sensor connection, but diagram a few posts earlier also has the voltage values (IDE07730) of that sensor and it seems to be 5V until it actually measures positive temperatures, then it dips which makes sense. Just don't know what made it actually measure non-negative temps, since the engine was running for a few secs already.
I'll try to fiddle around a bit with the wiring while recording voltage/temp. when ignition is on. If nothing changes and it stays at -50C, the sensor itself is probably faulty and not the wiring, since it should probably measure something close to outside temps?

I'm kinda curious, since I don't have too much knowledge about how the EGR really works and how the sensor values are used. I mentioned some of it in an earlier post already, on a different short test drive the car was stuttering/jumping in 3rd/4th gear (1200-1500 rpm) and the glow plug light came on (blinking). The glow plug light was gone after turning the engine off for a bit, but engine management light was on. Same faults codes. Is this something that could be caused by the faulty sensor, e.g. egr regulates how much exhaust gas is lead back depending on that sensor value?

Regardless, again, I'd like to thank you @mmi for helping with the troubleshooting! Hope this can be of use to someone in the future with a similar issue.
I'll def. keep this post up to date regarding whatever happens at the mechanics and what they end up changing.
cheers

 

[xcelrec]

Well, guess I can update this faster than I thought. Didn't see it when I last checked the sensor cable, since it was already kinda dark and you can only do so much with a flashlight. As you can see below, sensor starts out with -50C and 5V, immediately when I moved it, it jumped back to outside temps...
Looking at the sensor cable a bit closer, vw ran the sensor cable directly under some thin tubes. Guess the 150k km and vibration did the rest. The cable sheath was worn through and probably also the cable to a degree. Anyway, I probably broke it completely now as I couldn't get it back to reading correctly after a while. Few logs below. At least no new egr needed.

 

[mmi]

I'm kinda curious, since I don't have too much knowledge about how the EGR really works and how the sensor values are used. I mentioned some of it in an earlier post already, on a different short test drive the car was stuttering/jumping in 3rd/4th gear (1200-1500 rpm) and the glow plug light came on (blinking). The glow plug light was gone after turning the engine off for a bit, but engine management light was on. Same faults codes. Is this something that could be caused by the faulty sensor, e.g. egr regulates how much exhaust gas is lead back depending on that sensor value?

Thanks for clarification - good to know that flashing coil light was triggered.
Quite possible that the stuttering was caused by the fault. Unfortunately we don't know for sure how engine is supposed to handle sudden loss of data. Possibly changed to some kind of emergency operating mode, perhaps with reduced power.

Well, guess I can update this faster than I thought. Didn't see it when I last checked the sensor cable, since it was already kinda dark and you can only do so much with a flashlight. As you can see below, sensor starts out with -50C and 5V, immediately when I moved it, it jumped back to outside temps...
Looking at the sensor cable a bit closer, vw ran the sensor cable directly under some thin tubes. Guess the 150k km and vibration did the rest. The cable sheath was worn through and probably also the cable to a degree. Anyway, I probably broke it completely now as I couldn't get it back to reading correctly after a while. Few logs below. At least no new egr needed.

Yes, after a few seconds the sensor start to report plausible values - in the first log.

Anyways, always good when you can pinpoint the failing point - almost fixed now

 

[n10n]

Unfortunately we don't know for sure how engine is supposed to handle sudden loss of data. Possibly changed to some kind of emergency operating mode, perhaps with reduced power.

But we can speculate

The temperature sensors are obviously reading coolant temperatures as exhaust gases would be much more hot even shortly after starting.

SSP 564 mentions this:


It seems likely the temperature sensors are controlling EGR cooling. The sensible fault mode would be to run the cooling at max. That said, depending how severe a condition sensor fault is according to VW gods, power reduction might indeed be done as well.

 

[n10n]

The temperature sensors are obviously reading coolant temperatures

This seems premature conclusion as well. Looking at the IDE07729 stats over a 1.5h drive it peaks at 190° but the average and median are at modest <50°. I don't know what this measures but both air and water seem wrong... maybe a cooling fin or other structure?

CAN3.advanced_measuring_values_engine.IDE07729_egr_temperature
unit  count   ts_0      ts_n   val_0   val_n     min      max     avg  median  std_dev
   C  11954 2.3827 5630.9279 22.2000 76.2000 22.2000 190.7000 48.5593 47.0000  11.8700

Intriguing... now I probably have to dig in to understand the conditions for high peaking - if those could be avoided maybe it might help to avoid *some* EGR issues down the line. Especially if such temperature change is quick as might be the case since median is so low.

Edit: oh wow, there's high peaks in the trip beginning and end, very well regulated for the most part of the trip



I still have my EGR valve % scaling wrong but the activity is clear. Now I have to wonder if IDE07754 Exhaust recirculation valve 1 bank 1 is actually "Exhaust gas recirculation cooler change-over valve N345" as referred to by SSP 564. And if so, why is it letting EGR initially so hot before kicking in?

 

[mmi]

Intriguing... now I probably have to dig in to understand the conditions for high peaking - if those could be avoided maybe it might help to avoid *some* EGR issues down the line. Especially if such temperature change is quick as might be the case since median is so low.

Edit: oh wow, there's high peaks in the trip beginning and end, very well regulated for the most part of the trip

Indeed fascinating. Now I do see the behaviour also in my logs - haven't paid attention on that although tried to evaluate the EGR cooler blockage by recording everything related I could imagine.

The big dip in input temperature at 200 seconds is because of a lengthy downhill on my way always - have to keep foot off the throttle.
The EGR position I've used is the one I believe is the actual position of the EGR valve - now the positive/negative transition might have got an explanation.
Makes me wonder if this is the design to quickly warm up coolant entering into cabin heat exchanger.... it was +12 °C outside then.

I didn't see the peak at the end... but just checked only few logs... perhaps by letting engine idle when it will be colder...




PS. Apologies @xcelrec for slightly deviating from your issue - but it's still about your sensor and how to take advantage of it