Persistent DPF regeneration after timing belt replacement

Volkswagen Golf 7 1.6 TDI DDYA, 175,000 km, mostly highway miles.

Hello everyone.

I replaced the timing belt on my Golf 7 1.6 TDI. I loosened the pulleys of the high-pressure pump and camshaft, rotated them to their respective marks, installed the belt, and then tensioned it. Now, the pulleys are not aligned with their marks, which is how they should be.

I checked the error memory, but there's nothing stored in it.

Only he starts regenerating now, and it doesn't stop even after a long drive.

All the connectors are plugged in, and the hoses of the differential pressure sensor are not kinked or damaged.

Does anyone know what might be causing this?

Sure:
Reasons why the DPF is not regenerating

That happened right after the timing belt was replaced, so I drove about 125 miles (200 km) and it started happening immediately.

Hi there,
Have you double-checked the valve timing by using shims?
Does the engine regenerate, or is it only running at a higher RPM (due to air conditioning, energy management)? You can check this, for example, by reading the data from the particulate filter in the "Advanced Measurement Data" (soot load, distance since last regeneration). The regeneration status should also be visible there.
Knowing the model year and engine code would be helpful; then I might be able to compare it with my own vehicle's data.

During the timing chain replacement, an exhaust temperature sensor likely had to be removed. Does it still provide meaningful readings? It's possible that the post-injection system is running constantly because the sensor is reporting a temperature that is too low. The differential pressure sensor was probably also affected.
hg
Herbert.

This is a DDYA engine, manufactured in 2018, and the error memory is clear.

What are the sensors in the measurement unit? Also, what is a "Launch device"?

It's probably difficult to directly infer information from VCDS and apply it to a Launch diagnostic tool (which specific model?). Is there a list of available data parameters that can be accessed while the vehicle is running or with the ignition on?
hg
Herbert.

Can I tell you right away?

I'll double-check the timing settings on Saturday. Also, the problem was that the engine was still slightly warm, which isn't ideal.

I checked the valve timing, it was slightly off, but I adjusted it and now it's correct again. However, yesterday it started the same process after about 125 miles.

I tested the differential pressure sensor, and it reads 100 ohms. The temperature sensor reads 0 ohms when the engine is warm.

The differential pressure gauge looks good while driving, but the tester is showing a raw voltage of 0V at the sensor.

Error memory is empty.

Hi,

Have you already reviewed the article titled "DPF not regenerating" (technical article)?

Measuring the differential pressure sensor with an ohmmeter is technically pointless from an electrical engineering perspective.

0 Ohm temperature sensor: Then the exhaust gas temperature sensor is probably faulty. Did you use the correct measurement range on the multimeter?

Check the measured values via diagnostics in the engine control unit and put your multimeter away.

Best regards, Rainer.

He says that while I'm driving fast on the highway, VCDS displays something.
Sensor 1: 700 degrees Celsius; Sensor 2: 200 degrees Celsius (after the catalytic converter).

Marco_mk75 wrote:

Then he tells me, while I'm driving fast on the highway, using VCDS. Sensor 1: 700 degrees, and Sensor 2: 200 degrees after the CAT

.
Okay.

And why does the upstream oxygen sensor have a resistance of 248.7 ohms? Are they both the same?

Marco_mk75 wrote:

And why does the upstream oxygen sensor have a resistance of 248.7 Ohms? Are they both the same type?

I have no idea, but before you make a whole doctoral thesis out of it and measure incorrectly, just check the temperature readings in the engine control unit. If the car has been standing for a while, both temperatures should display approximately 30°C if the ambient temperature is 30°C.

I'm just surprised that the pre-catalyst has a temperature of 700 degrees and the post-catalyst has a temperature of 200 degrees.

Something's not right; it can't lose that much temperature so quickly, less than 500 degrees.