CAYC Sensor: Troubleshooting Turbocharger Boost Issues

Hello,
My sister-in-law's Seat Ibiza is having problems.
This error keeps occurring sporadically and without any apparent trigger.

7380 - Charge pressure sensor (G31).
P0236 00 [036] - implausible signal.

She took her car to a workshop weeks ago, where they replaced the entire EGR unit and the turbocharger pressure sensor.
I cannot say what error was present at that time.

The wiring from the sensor to the MSG is continuous and does not cause any measurable resistance.
The new Bosch sensor I installed immediately triggered a stored error code after installation.

Tuesday, November 16, 2021, 7:00:23 PM: 23565
VCDS - A Windows-based VAG/VAS emulator that runs on Windows 10 x64.
VCDS version: DRV 20.12.0.3
Data as of: 20210211 DS322.1
www.Ross-Tech.de


Vehicle Identification Number (VIN): VSSZZZ6JZBR191609 License Plate: ANIKA



"Die Sonne scheint hell und warm. Die Vögel zwitschern fröhlich in den Bäumen. Ein leichter Wind weht durch das Gras. Es ist ein perfekter Tag für einen Spaziergang."
"Die Sonne scheint hell und warm. Die Vögel zwitschern fröhlich in den Bäumen. Ein leichter Wind weht durch das Gras. Es ist ein perfekter Tag für einen Spaziergang."


Address 01: Engine Control Module
Label file: DRV\03L-906-023-CAY.clb
Control unit part number: 03L 906 023 LD. Hardware version: 03L 906 023 Q.
Component and/or version: R4 1.6L TDI H33 9978.
Encoding: 00114016002400080000
Operating number: WSC 131071 1023 2097151.
ASAM Dataset: EV_ECM16TDI02103L906023LD 003012 (SE25)
ROD: EV_ECM16TDI02103L906023LL.rod
text
VCID: 73E3B198DAE9251C0D-8026
"One error found:"

7380 - Charge pressure sensor (G31).
P0236 00 [032] - Implausible signal.
Occasionally - unconfirmed - checked since last deletion.
Environmental conditions:
Error status: 00000001
Error priority: 2
Error frequency: 2.
Date: 2000.00.00
Time: 00:00:00

Motor speed: 0.00 rpm.
Normalized load value: 0.0%
Vehicle speed: 255 km/h
Coolant temperature: 42 °C.
Intake air temperature: 5 °C
Ambient air pressure: 1010 millibars.
Voltage at terminal 30: 12.424 V.
Lost learning counter via OBD: 40.
Boost pressure: Actual value - MAP (Manifold Absolute Pressure): 200.00 hPa.
Boost pressure: Setpoint - MAP_SP_MMV: 200.00 hPa.
Ambient air pressure: 101 kPa absolute.
Particle filter: Differential pressure - DPF: 6.47 hPa.


Readiness: 0 0 0 0 0
Saturday, November 20, 2021, 3:22:50 PM: 0.23565
VCDS - A Windows-based VAG/VAS emulator that runs on Windows 10 x64.
VCDS version: DRV 20.12.0.3
Data as of: 20210211 DS322.1
www.Ross-Tech.de


Vehicle Identification Number (VIN): VSSZZZ6JZBR191609 License Plate: ANIKA



"Die Sonne scheint hell und warm. Die Vögel zwitschern fröhlich in den Bäumen. Ein leichter Wind weht durch das Gras. Es ist ein perfekter Tag für einen Spaziergang."
"Die Sonne scheint hell und warm. Die Vögel zwitschern fröhlich in den Bäumen. Ein leichter Wind weht durch das Gras. Es ist ein perfekter Tag für einen Spaziergang."


Address 01: Engine Control Module
Label file: DRV\03L-906-023-CAY.clb
Control unit part number: 03L 906 023 LD. Hardware version: 03L 906 023 Q.
Part and/or version: R4 1.6L TDI H33 9978.
Encoding: 00114016002400080000
Operating number: WSC 131071 1023 2097151.
ASAM Dataset: EV_ECM16TDI02103L906023LD 003012 (SE25)
ROD: EV_ECM16TDI02103L906023LL.rod
text
VCID: 73E3B198DAE9251C0D-8026
Two error codes found:

7380 - Charge pressure sensor (G31).
P0236 00 [036] - implausible signal.
Occasionally - unconfirmed - checked since last deletion.
Environmental conditions:
Error status: 00000001
Error priority: 2
Error frequency: 2.
Mileage: 170,917 km
Date: 2119.14.23
Time: 00:06:31

Motor speed: 0.00 rpm.
Normalized load value: 0.0%
Vehicle speed: 255 km/h
Coolant temperature: 16 °C
Intake air temperature: 7 °C
Ambient air pressure: 1000 millibars.
Voltage at terminal 30: 11.181 V.
Lost learning counter via OBD: 40.
Boost pressure: Actual value - MAP (Manifold Absolute Pressure): 200.00 hPa.
Boost pressure: Setpoint - MAP_SP_MMV: 200.00 hPa.
Ambient air pressure: 100 kPa absolute.
Particle filter: Differential pressure - DPF: 0.00 hPa.

7382 - Charge pressure sensor (G31).
P0236 00 [096] - implausible signal.
Occasionally - unconfirmed - checked since last deletion.
Environmental conditions:
Error status: 00000001
Error priority: 2
Error frequency: 3.
Date: 2000.00.00
Time: 00:00:00

Motor speed: 0.00 rpm.
Normalized load value: 0.0%
Vehicle speed: 255 km/h
Coolant temperature: 22 °C.
Intake air temperature: 6 °C
Ambient air pressure: 1010 millibars.
Voltage at terminal 30: 12.311 V.
Lost learning counter via OBD: 40.
Boost pressure: Actual value - MAP (Manifold Absolute Pressure): 1129.50 hPa.
Boost pressure: Target value - MAP_SP_MMV: 1129.50 hPa.
Ambient air pressure: 101 kPa absolute.
Particle filter: Differential pressure - DPF: 0.00 hPa.


Readiness: 0 0 0 0 0

Thank you in advance for your ideas and help.

Hello,

Check for wear points on the wiring harness and loose connections at the connectors. Are the correct operating voltages present for the sensor?

What pressure is the sensor measuring when it's stationary? One would expect it to be approximately the same as the ambient pressure measured by a separate pressure sensor.

Best regards, Rainer.

Hello Rainer,

This morning, I unsuccessfully inspected the engine wiring harness for any signs of abrasion or other abnormalities. All connectors are also securely fastened, and the contacts are properly locked in place within the connectors.
The sensor reads 4.99V when the ignition is on.

This morning, I experimentally connected a faulty sensor, which immediately caused the same error to appear in the control unit. It was already displaying a reading of 1168 mbar at ignition.

It's noticeable that with the correct sensor, when ignition is activated, sometimes it displays 200 hPa and other times it displays 1004 hPa.
Wenn 1004 angezeigt werden und ich Druck auf den Sensor gebe ändert sich dieser Wert. No, not with 200.

Best regards.
Sören.

Ok, du kannst den Fehlerfall also schon mal reproduzieren. That's good.

I suspect the boost pressure sensor outputs an analog value. For example, 0V for 0 mbar (vacuum) and 5V for a maximum of, say, 2500 mbar. At an ambient pressure of 1000 mbar, you should measure approximately 2V with that example. At only 200 mbar, you would see just 0.4V.
(The actual values you see will likely be different, for example, because the sensor might have a range up to 3 bar.)

Can you measure that again? Or is the engine control unit just giving incorrect readings?

Generally speaking, it can probably be said that: if the wiring and sensor have been ruled out as potential causes of the problem, then the most likely culprit is the control module (MSG). However, this type of error is relatively rare in this forum. Therefore, the suggestion is to first measure the voltages (at the sensor and at the MSG end of the cable) in both the normal operating condition and the fault condition.

I probably didn't express myself clearly.
I could only trigger an error code in the control unit by using the incorrect sensor. With the correct sensor, the issue is intermittent and not reproducible.
If the displayed boost pressure is 200 hPa, no error will be logged.

Okay, I understand. But can you reproduce the 200hPa with the correct pressure sensor? If so, that would be the point where I would start taking measurements. If it's showing such strange values, then there's obviously already a fault, even if the MSG hasn't yet recognized it as an error. So, that's the starting point for troubleshooting. Start by reading and recording data at a high rate, and simultaneously check all cable connections, connectors, and the MSG itself, looking for any changes. If you don't find anything, then measure whether the 5V and signal voltage are identical to the faulty state.

Where does the sensor come from? Is it an original part from a reliable source, or is it a replica?
It still only involves wiring, a sensor, and the MSG (Message Sending Unit).

Regarding... The data in the MSG is also noteworthy. Why is the date sometimes in the year 2000 (understandable = not unset) and sometimes in the year 2119? Are there any other things that are striking in the MSG?

The value of 200 hPa is achieved with the correct Bosch sensor. As soon as I start the engine, a plausible boost pressure is immediately displayed.

It's also interesting that the boost pressure is displayed as 200 hPa, while the intake manifold pressure is shown as 100 kPa.
When the engine is started and a boost pressure of 1000 mbar is displayed, if I then apply pressure to the sensor, the displayed boost pressure and intake manifold pressure both increase to the same value.
If the ignition is on and a value of 200 hPa is displayed, only the indicated intake pressure increases.

Therefore, I believe the issue cannot be with the sensor itself, because the value is being measured by the same sensor.

I haven't noticed any anomalies in the engine control unit yet.

Hello,

I'm wondering why a "faulty" sensor was installed in the first place, and why nothing works anymore with the "correct" one.

It sounds like a failed tuning attempt, trying to integrate an LDS with a wider measurement range.

Tip: There are limits to the plausibility of measured voltage values. It may be necessary to investigate this further.

Furthermore, I would like to point out that this is not a forum for "fixing my tuning problems."

Best regards, Rainer.

Hello, I once had a vehicle where the differential pressure sensor was the cause of the problem. Several vehicles are connected to the same power supply. Normally, the engine control unit detects errors in this regard (sensor reference voltage), but in my case, it didn't. Because the error occurs very sporadically, it is very difficult to diagnose. If possible, try replacing it as a test.

Best regards,
Dago

Hello, Rainer.

The vehicle is in absolutely original condition and has not undergone any modifications or tuning attempts!

I only connected the incorrect sensor temporarily to test whether it would immediately trigger an implausible boost pressure error when the ignition is turned on, and to ensure that the displayed boost pressure and intake manifold pressure are measured by the same sensor. My intention was to narrow down the problem to the sensor or rule it out altogether.

With the original system, it only happened sporadically. Now, the car ran perfectly for 8 days before the problem reappeared yesterday.

Of course, I can now measure the output voltage of the sensor at all possible operating pressures and check its plausibility.
However, the boost pressure and intake manifold pressure are measured by the same sensor. If the engine control unit always displays the intake manifold pressure correctly but only partially shows the boost pressure, then it cannot be the sensor itself.
If I have a flaw in my thinking, I am happy to be corrected and learn something better.

@ Dago
I think your idea is good and plausible .
Both the boost pressure sensor and the differential pressure sensor receive their operating voltage from pin T94/14 of the MSG (Main System Module). This may cause a slight voltage drop at some level within the MSG, which could be the cause of the error.
I will test that next.

Best regards.
Sören.

Hello,

Could the problem be solved?
My father's Altea (with license plate CAY) has exactly...
the same problem...

Hello,
Unfortunately, the problem could not be properly resolved. Since the car has suffered a total economic loss, I am unable to continue testing.
I replaced the differential pressure sensor back then, which resulted in the error only reappearing once within 8 weeks (until the damage occurred).

Hello,
Thank you for the response. I've looked into the issue more closely, and it seems there's a problem with the 5-volt supply voltage from the boost pressure sensor/differential pressure sensor. When the ignition is on or the engine is running, only 4.76 volts are present (should be 4.8 - 5.2 volts), meaning the boost pressure reading is not even close to the atmospheric pressure (over 50 mbar). After checking at MST pin 14, I suddenly get 5 volts, and both the sensors show nearly identical readings for boost pressure and atmospheric pressure. I've ruled out a wiring problem. I suspect a faulty MST module; currently, the Altea is functioning as it should...

Hi there,

Quote:

With the ignition on or with the engine running, there are only 4.76 volts (should be 4.8 - 5.2 volts), which means that the boost pressure value is not nearly equal to atmospheric pressure, i.e., > 50 mbar.

With what instrument were 4.76 volts measured, and with what tolerance?
What pressure value does the boost pressure sensor display when the engine is started?
hg
Herbert.

Hello, I measured it directly at the LDS using a multimeter.

Please update the VCDS version and then post a complete scan of the vehicle here afterwards.

Until then, the suspicion of a pirated copy remains due to the outdated version. Since the forum owner makes a living from selling VCDS software, there will be no support provided for this.