P0697 on a 2015 Volkswagen Golf TDI indicates a fault in the sensor reference voltage "C" circuit.

[rigelcosto]

Hello Everyone!

I cleared the code 2 weeks ago after noticing the battery connection was loosened. Battery recharged and installed back. After that, the code never appeared again until 3 days ago. Recent MIL on indicates ECU sensor reference voltage C - open circuit. Using VCDS I tested all those sensors, some of them has no voltage at all, is that normal? Anyone seen this before ?

EGR TEmp sensor 1 B1:raw voltage 0.0mV (no the same that 0mV like others below)
EGR TEmp sensor 2 B1:raw voltage 3807.2mV
NOx sensor before SCR catalytic converter 0mV
NOx sensor after SCR catalytic converter 0mV
Glow_period_control_unit_calculated_glow... 0mV
Glow_period_control_unit_enercy_integrat... 0mV

Thankyou for any pointers / help given !!

 

[Uwe]

a fault

What fault? Please post a scan.

-Uwe-

 

[rigelcosto]

Tuesday,22,April,2025,15:13:16:35756
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 25.3.1.1 (x64)  HEX-V2 CB: 0.4671.4
Data version: 20250415 DS365.0
www.Ross-Tech.com


VIN: 3VW2A7AU1FM028814   License Plate:


Chassis Type: AU-VW37 (5Q0)
Scan: 01 02 03 08 09 15 16 17 19 42 44 47 52 55 5F 75

VIN: 3VW2A7AU1FM028814   Mileage: 135500km-84195miles

01-Engine -- Status: Malfunction 0010
02-Auto Trans -- Status: OK 0000
03-ABS Brakes -- Status: Malfunction 0010
08-Auto HVAC -- Status: Malfunction 0010
09-Cent. Elect. -- Status: Malfunction 0010
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: Malfunction 0010
42-Door Elect, Driver -- Status: OK 0000
44-Steering Assist -- Status: Malfunction 0010
47-Sound System -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
55-Headlight Range -- Status: OK 0000
5F-Information Electr. -- Status: Malfunction 0010
75-Telematics -- Status: OK 0000
-------------------------------------------------------------------------------
Address 01: Engine (J623-CRUA)       Labels:. 04L-907-309-V1.clb
   Part No SW: 04L 997 022 N    HW: 04L 907 309
   Component: R4 2.0l TDI   X23 9459 
   Revision: 85X23---    CVN: B5ADD45238D3FF82
   Coding: 011D0012032410080000
   Shop #: WSC 00000 000 00000
   ASAM Dataset: EV_ECM20TDI01104L997022N 004002
   ROD: EV_ECM20TDI01104L997022N.rod
   VCID: 3B2324CBA3ED1A129A8-806E
   VINID: 0E69C244746505674008820110E1C4792C

1 Fault Found:
4125 - Sensor Reference Voltage C
          P0697 00 [10101111] - Open Circuit
          MIL ON - Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Priority: 2
                    Fault Frequency: 1
                    Mileage: 135500 km
                    Date: 2025.04.22
                    Time: 15:09:27

                    Engine speed: 983.50 /min
                    Normed load value: 37.3 %
                    Vehicle speed: 0 km/h
                    Coolant temperature: 93 °C
                    Intake air temperature: 64 °C
                    Ambient air pressure: 1010 mbar
                    Voltage terminal 30: 13.340 V
                    Unlearning counter according OBD: 40
                    Turbocharger 1 turbine input: temp. sensor 1: B1: raw value: 255.8 °C
                    Turbocharger 1 turbine output: temp. sensor 1: B1: raw value: 216.5 °C
                    Particulate filter input: temp. sensor 1: bank 1: raw value: 203.2 °C
                    Particulate filter output: temp. sensor 1: bank 1: raw value: 195.3 °C
                    EGR temp. sensor 2: B1: raw value: 89.5 °C
                    Shut-off timer: last engine shut-off time: 3 s

Readiness: 1 1 0 1 0

 

[Uwe]

OK, "Open Circuit".

I know you've been to this thread where I explained that fault code:

https://forums.ross-tech.com/index.php?threads/48933/#post-397315.

-Uwe-

 

[rigelcosto]

Ok thank you, it should be that sensor, because otherwise multiple sensors were affected.

 

[rigelcosto]

Hi guys, after a while, I came back with my story about this code. After reviewing all sensors available in the exhaust system, no physical damage was noticed. But the code is still there. Solution: Add DPF cleaner, available in auto parts, to the diesel tank. Run the car for about 30 miles, in 4th gear, 60 M/H, and the problem was solved.

 

[Uwe]

Solution: Add DPF cleaner, available in auto parts, to the diesel tank. Run the car for about 30 miles, in 4th gear, 60 M/H, and the problem was solved.

DPF cleaner in the fuel tank fixed electrical problems? I don't think so!

-Uwe-

 

[rigelcosto]

I have not said that. I think that the differences between the sensors before and after the DPF were reading different voltages, and it can be interpreted as an open circuit, no idea, but for sure it solves the code.

 

[golfi_vend]

My experience with "C" circuit is that it's usualyy DPF Difference sensor issue.

 

[NEtech]

Also look at the thick engine wiring harness, is touching somewhere.

 

[rigelcosto]

I had reviewed that car all over the engine bay, all cables were moved, and 3 sensors were replaced (OEM parts) because of physical damage, and the code was still there. I read something about this matter related to the DPF filter and went to autoparts for the foam version of the cleaner, but ended up using the other one that is added to the fuel tank. Problem solved until now, 12K miles after.

 

[golfi_vend]

Sensor C fault fixed with DPF clean -> Total BS!!!