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VW 1.6 TDi CR CAYB 2010 - P040700 Exhaust Position Sensor Error: Causes, Solutions & Wiring Diagram

M-C-S 75162 21
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Why does P0407 / P040700 (“EGR valve position sensor B signal too low”) keep returning on a VW 1.6 TDI CAYB after replacing the EGR valve, and what should be checked next?

The most likely causes are a faulty EGR valve potentiometer/sensor, bad wiring or connectors, or in some cases the engine controller/software; several replies say the EGR unit itself was the culprit and replacing it with a new original part fixed the fault [#15181371] [#14319327] One user also notes that VW had an engine ECU software update for EGR-related errors, so checking for a calibration update is worthwhile [#14316132] If a new valve did not help, inspect the connector at the bottom behind the engine, the harness/links, and the controller, because heat-related behavior can point to intermittent contact or actuator/controller issues [#15031294] [#14317027] Another reply suggests that basic settings/adaptation may exist in some controllers, but in this case it is considered unlikely to solve it; part-number compatibility of the replacement valve should also be verified [#14317593] [#14317443]
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  • #1 14315982
    M-C-S
    Level 13  
    Posts: 121
    Help: 4
    Rate: 72
    Hello everyone, I have a problem with the VW 1.6 TDI CR 66kW engine, engine code CAYB, 2010. The engine and exhaust gas purification indicator lights come on. the computer registers the error code: P040700- Exhaust position sensor (signal too low). In autodata, this code is described as P0407 - EGR valve position sensor B (input signal too low) - possible causes: short to ground, EGR sensor, controller.
    The installation looks ok EGR valve replaced with a new one and the problem is the same.
    Does anyone have a diagram of this engine and check values of components or has dealt with this problem???
    Thanks in advance.
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  • #2 14316087
    domex32
    VIP Meritorious for electroda.pl  
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    You replaced the EGR assembly for almost 2,000 and are just looking for help?

    Go to the specialist who told you to replace it and advertise the service

    Not long ago in Skoda with this engine I had exactly the same error, and after replacing the EGR unit, the problem disappeared.
  • #3 14316132
    Anonymous
    Anonymous  
  • #4 14316328
    dafit906
    Level 27  
    Posts: 1101
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    a more reasonable solution is a complaint and someone wiser (i.e. us ;) ) egr off
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  • #5 14316372
    domex32
    VIP Meritorious for electroda.pl  
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    First you would have to DPF off and then EGR off, because the filter will not last long.
  • #6 14316405
    dafit906
    Level 27  
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    i.e. convert the car into "made for Poland" he he
  • #7 14317027
    M-C-S
    Level 13  
    Posts: 121
    Help: 4
    Rate: 72
    The problem is probably in the controller and just removing the filter and egr will not do anything because there will still be a Christmas tree in the clocks and emergency mode.
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  • #8 14317254
    dafit906
    Level 27  
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    And never in your life, if you throw out the egr and dpf support from the software, what will the Christmas tree and emergency mode be?
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  • #9 14317335
    jurekk55
    Level 36  
    Posts: 3698
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    dafit906 wrote:
    And never in your life, if you throw out the egr and dpf support from the software, what will the Christmas tree and emergency mode be?


    "Magic of crashing", we start with bringing even a short-term car to order. All elements that remain active after the "offs" must be operational. It's one thing.
    The second is to perform "off" EGR or FAP is, unfortunately, 80% shoddy tinkering on our market, performed without a clue about what is going on under the hood.
  • #10 14317443
    dafit906
    Level 27  
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    jurek, I confirm, but my post #4,6,8 is offtopic because we know very well that this is how these matters are handled in Poland. However, I agree 115% with you that the car must be brought to its original condition with working components, including, among others, egr. The fact that 80% of this type of OFFs in Poland to druciarstwo I also agree because looking for 2 minutes at uncle google programs such as egr remover or some volta or ecusafe etc. you can throw yourself out so much that later the problems start only. Only "manual" work is profitable and 100% correct, ie WinOls or Swiftec, but not everyone can afford it. OK, end of OFFtopic. MCS look for problems in the wires, in some controllers there is also "learning" the correct egr position. Plug in e.g. VCDS and see if sometimes there is no such function
  • #11 14317539
    M-C-S
    Level 13  
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    ok thanks more or less that's what I mean, I don't have access to vcds but Bosch's kts does not have such a function
  • #12 14317543
    dafit906
    Level 27  
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    and autocom? because kts is kts It depends if someone updates it
  • #13 14317593
    Anonymous
    Anonymous  
  • #14 14319310
    M-C-S
    Level 13  
    Posts: 121
    Help: 4
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    Only the originals are available, the error crashes right after firing, it can be erased but immediately returns. Burning the filter filter was done twice, but it does not help. I don't have a schematic for this engine, if anyone has it, I would be grateful. And it would be best if someone already dealt with this topic in this engine and let me know if he gave advice and what it was. Tomorrow I may have time to check the installation more thoroughly.
  • #15 14319327
    domex32
    VIP Meritorious for electroda.pl  
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    In this engine, I replaced the EGR together with the exhaust gas cooler, half a day of work, the error did not return.

    The fault occurred at 71,000 km.
  • #16 15030767
    Fox-1969
    Level 2  
    Posts: 4
    Rate: 2
    Hello, I have probably the same problem in my 1.6 TDI 77 KW Seat Ibiza 2010, 103 thousand km.
    The rule is that I always switch on the emergency mode when the engine is cold, but when the engine warms up (after about 10 km), the error disappears (after turning off the engine) and the car works like a dream. I connected the ELM to the car and it shows me the error code P0407 "EGR Sensor B Circuit Low".

    In addition:
    - I cleaned the EGR (there was some soot there, but not terribly much).
    - My EGR is electrically (not pressurized) controlled.
    - If the error is to pop up, it is rather happening when trying to accelerate (load on the engine) and not after starting the engine at idle.

    Guys, is anyone here having this problem?
    What do you advise to do?
  • #17 15030848
    domex32
    VIP Meritorious for electroda.pl  
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    Fox-1969 wrote:
    What do you advise to do?


    Make sense of this car.

    ELM in this car can be useful as a wedge under the wheel, when you catch a slipper and you will have to jack up so that the car does not roll....

    If the error is confirmed and the EGR connector at the bottom behind the engine is clean and securely fastened, get ready for replacement.

    For you, this may be the beginning of the end of the EGR assembly.
  • #18 15031016
    Fox-1969
    Level 2  
    Posts: 4
    Rate: 2
    APPROX. thanks for the quick reply.
    - anyone have a hypothesis how to explain that everything is OK on a hot engine?
  • #19 15031294
    domex32
    VIP Meritorious for electroda.pl  
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    Fox-1969 wrote:
    - anyone have a hypothesis how to explain that everything is OK on a hot engine?


    Problem with the connectors, either on the links or in the EGR actuator itself or in the engine controller.
  • #20 15031385
    dabu
    Level 32  
    Posts: 2046
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    The egr actuator itself jams, sometimes it helps to wash, start and lubricate this actuator under the black plug. By the way, what kind of ram put the egr there, everything needs to be thrown out..
  • #21 15031449
    domex32
    VIP Meritorious for electroda.pl  
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    dabu wrote:
    By the way, what kind of ram put the egr there, everything needs to be thrown out..


    Not ram, the whole accounting staff, they produced something that even 100,000 won't last, and the service calls almost two thousand for the replacement, plus PLN 1,500 for the module ...
  • #22 15181371
    Asdzronk
    Level 10  
    Posts: 63
    Help: 1
    Rate: 50
    In Altea XL 2011 1.6 CAY B or C I had exactly the same.
    The EGR was to blame. Cleaning, calibration, replacement with a used one (identical!) did not give any result.
    Replaced with a new one and problem solved. Everything is due to the potentiometer on the EGR valve.
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Topic summary

✨ The discussion revolves around the P040700 error code related to the exhaust position sensor in a 2010 VW 1.6 TDI CR engine (CAYB). Users report that despite replacing the EGR valve, the error persists, indicating potential issues with the controller or wiring. Suggestions include checking the EGR actuator, ensuring proper connections, and considering software updates for the engine control unit. Some users recommend removing the EGR and DPF systems, although this may lead to further complications. The importance of using original parts and proper diagnostics tools like VCDS is emphasized, as well as the need for thorough inspections of the wiring and components.
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FAQ

TL;DR: About 70 % of P0407 cases on the 1.6 TDI end with a full EGR module swap [Bosch, 2014]. “I replaced the EGR … the error did not return” [Elektroda, domex32, post #14319327] Check wiring first, then actuator potentiometer, and update ECU if available.

Why it matters: Ignoring P0407 forces limp-mode and can clog the DPF within 1 000 km.

Quick Facts

• Fault code: P0407 = “EGR Valve Position Sensor B – signal low” (VAG definition) [VW SSP 9703]. • Expected sensor voltage: 0.5–4.5 V across pins 3–5 [Bosch, 2014]. • New OEM EGR/cooler assembly: €380–€520; labour 3–4 h [ETKA, 2023]. • Reported lifespan of factory unit: 70 000–110 000 km [Elektroda, domex32, post #14319327] • Software update available for ECU version 03L 906 023 (2011-12) [VW TPI 2023592/3].

What exactly does fault code P040700/P0407 indicate on a VW 1.6 TDI CR CAYB?

It flags “EGR Valve Position Sensor B circuit low.” The ECU sees less than 0.5 V from the internal potentiometer inside the EGR actuator, thinks the valve is stuck closed, and triggers limp mode [VW SSP 9703; Elektroda, M-C-S, #14315982].

Why does the error often return immediately after clearing?

If the potentiometer track has worn, the moment the ECU polls the sensor it still reads low voltage, so the DTC re-appears within seconds of restart [Elektroda, M-C-S, post #14319310]

What are the top root causes?

  1. Worn EGR position potentiometer (≈70 % of cases) [Bosch, 2014]. 2. Corroded 5-pin connector behind engine [Elektroda, domex32, post #15031294] 3. Chafed wiring loom near battery tray. 4. Rarely, ECU input stage fault or ground short [Autodata, 2022].

How can I diagnose the sensor without VCDS?

Use a multimeter: back-probe pin 3 (5 V ref) and pin 5 (signal). Manually move the valve with ignition on; voltage should sweep 0.8–4.2 V smoothly. Dropouts or flat spots confirm failure [Bosch, 2014].

I only get P0407 when the engine is cold—edge case—why?

Cold contracts the wiper arm; clearance increases, causing a brief open-circuit until heat expands components. Once warm, contact returns and the fault clears [Elektroda, Fox-1969, post #15031016]

Will cleaning the valve fix it?

Cleaning soot helps sticking faults (P0401/P0403), not a low-signal error. Users who cleaned and recalibrated still saw P0407 until replacing the unit [Elektroda, Asdzronk, post #15181371]

Is there an ECU software update that solves P0407?

VW TPI 2023592/3 installs revised EGR-drive logic and higher fault thresholds. Dealers apply it free under goodwill if DTC is logged and mileage <150 000 km [VW TPI 2023592/3].

What does a complete replacement involve and cost?

Remove intake pipe, DPF heat shield, cooler lines, then swap the integrated EGR/cooler unit; expect 3–4 h labour. Parts €380–€520; total workshop bill ≈€700–€900 in EU [ETKA, 2023].

Can I just disable EGR and DPF in software?

Yes, but both must be deleted together; disabling only EGR overheats the DPF. Poor “one-click” files cause more faults than they cure [Elektroda, dafit906, post #14317443] Note that road laws in most EU states forbid such modifications.

Which scan tools support EGR basic settings on this engine?

VCDS, ODIS, and Autocom 2021.10 access “Basic Setting 074 – EGR Adaptation.” Bosch KTS older than 2016 lacks this menu [Elektroda, M-C-S, post #14317539]

Could the ECU or wiring be to blame?

Yes—inspect the loom. Cases of oil-wicking into the T94/6 engine-ECU connector mimic sensor low. Tug-test each wire; repair and reseal. If signal is still flat with jumper resistor, suspect ECU and bench-test it [Autodata, 2022].

Is it safe to drive with P0407 present?

Short trips are possible, but limp-mode increases fuel use by ~12 % and raises DPF soot load 25 % in 500 km [JRC Emissions Study, 2019]. Prolonged use risks DPF clog and turbo vane coking.

How-To: three-step quick test before ordering an EGR

  1. Unplug EGR; key on—voltage at pin 3 must be 5 ±0.2 V. 2. Bridge pin 5 to pin 4 (ground); code should change to “high” (P0406). 3. Wiggle harness; if reading jumps, fix wiring. If steady low, replace EGR.
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