OBD Readiness: How Auto Repair Shops Implement It

Hello,

Apparently, TDIs manufactured from 2004 onwards are supposed to be OBD-compatible. This means that, starting in 2007, TÜV inspectors connect to the engine control unit (ECU) during the vehicle inspection (AU), read data such as error codes, and still allow the vehicle to pass, as an inspector told me in advance.

A key part of the OBD system is the OBD readiness code. This code can be read, for example, in memory address 17, and it should contain only three bits set to '1' in all fields, with the remaining bits being '0'.
00000000 / 00000110 / 10000000 / 00000000

I suppose that the TÜV (German technical inspection authority) also checks the emission control system during the inspection, and sends customers without a valid sticker away if the code looks different.
According to the relevant instructions (SSP 315, pages 44, 47, and 49), workshops are instructed to only hand over vehicles to customers if the exact values are recorded in the maintenance record (MWB 17), meaning that the OBD readiness code is fully set.

Immediately after clearing the error memory, three additional bits are set to 1, indicating that internal diagnostics of emission-related systems have not yet been successfully completed – but this does not necessarily mean that the systems are faulty!

To complete these diagnostic tests, a specific driving cycle must be run three times.
-> Ignition off for at least 5 seconds.
-> Turn the ignition on for at least 5 seconds without starting the engine.
-> 20 sec lang mit 42 km/h im 3. Roll the dough.
-> dann eine Vollgasbeschleunigung im 3. Range up to 3500 rpm.
-> then letting the car roll freely in 5th gear, from 2800 to 1200 rpm.

If the readiness diagnostics do not indicate any malfunctions, the "test in progress" bits are also changed from 1 to 0 by the MSG, indicating that the test is complete, and the code appears as described above.

I once went through the whole process with my car and realized that the driving cycle requires a significant amount of "break-in" time outside of a dynamometer.
3500 rpm in 3rd gear is already almost 100 km/h.
To initiate the acceleration phase in 5th gear at 2800 rpm, you need to accelerate further to approximately 140 km/h (i.e., get onto the highway), and the end of the phase at 1200 rpm corresponds to about 60 km/h. This means that on the highway, you'll become an obstacle to traffic unless you happen to encounter a suitable traffic jam.

Luckily, there's a highway construction site near me where the speed limit is reduced to 40 km/h at the exit, followed by unrestricted driving: it's perfect for performing the OBD readiness driving cycle on the road.

My question:
How do workshops, for example, in urban areas, handle this?
Spending hours driving around to reach a spot where the cycle is possible, and it just so happens that the traffic conditions also allow it .
Or are you running the cycle specifically on a test bench?
Does this whole thing also work in a more limited setting on a country road, for example, using the acceleration phase in 4th gear from 2800 to 1500 rpm instead of 5th gear from 2800 to 1200 rpm?
Or are you relying on the customer unknowingly setting the readiness code at some point during their trips, if their driving profile happens to match the cycle? It would certainly be embarrassing if that hadn't happened by the next inspection.

Hi,

I was also surprised by the alleged driving cycle. It was particularly strange that, after only about 30 km of driving (speed NEVER exceeding 110 km/h) and engine speed NEVER exceeding 3000 rpm, all the readiness codes displayed "Passed."

As far as I know, the inspector is running the engine at full throttle so that the idle speed can be checked.

Regards,
Sure, here is the translation of the text from German to English:

"Micha"

Mephisto wrote:

It was particularly strange that, after only about 30 km of driving (speed NEVER exceeding 110 km/h) and engine RPM NEVER exceeding 3000, all the readiness codes displayed "Passed".

Well, presumably, the testing procedures are somewhat tolerant of deviations from the driving cycle. For example, a speed difference of 42 + / 5 km/h, and an engine speed of 3000 - 4000 rpm might be sufficient as the end of the acceleration phase...
Because if the requirements had to be met with 100% precision, it would probably take at least 10 attempts in real-world traffic to achieve even a single valid cycle – which is impractical.

The question is, what specific deviations will be tolerated...

Does that mean you travel approximately 30 km just to set the readiness code? That's at least half an hour of a technician's time that the customer has to pay for, just for that... well, minus the usual time for test drives.

The great thing is that you're working with VAG models or on VAG systems, and for every OBD-2/EOBD VAG model, there's a readiness procedure, and normally that means the machine doesn't have to move even a millimeter.

For example, the current 2.0L TFSI and 3.2L FSI engines are really great.

...simply set the MWB 200 to the default settings, then keep your foot on the gas and brake for 4-5 minutes (refer to the MWB instructions for details), and the engine control unit will virtually simulate the entire driving cycle.

Okay, that was the example for "extremely simple," but in principle, it's not much different for almost all other models, and there are just these specific procedures involved.

Ulf, which medical codes are particularly interesting to you at the moment regarding these procedures?

Sebastian@OpenOBD wrote:

...simply set the MWB 200 to the default settings, then keep your foot on the gas and brake for 4-5 minutes (follow the instructions in the MWB manual), and the engine control unit will virtually run through the entire driving cycle.

Well, that's cute...

Quote:

Ulf, which specific medical codes (MKB) are particularly interesting to you at the moment regarding these procedures?

Currently, I only have my Polo 9N ASZ: Model year 2004, engine code 038 906 019 LA.

ulf wrote:

Well, that's cute...

As I said, this is the extreme case of simplicity.

ulf wrote:

Currently, only my Polo 9N ASZ: Model year 2004, engine code 038 906 019 LA

According to VAG, the entire process should proceed as follows at the ASZ.

- Ignition ON, Engine OFF.
- Read the readiness code (MWB 017).
- Check and clear fault codes (clearing resets the readiness codes).
- Coolant temperature above 80°C.

- Ignition OFF (for at least 6 seconds).
- Ignition ON, Engine ON.
- Engine idling.
- Increase the motor speed to 2450-2850 RPM and maintain this speed for at least 10 seconds.
- Engine idling.
- Increase the motor speed to 1600-1800 RPM and maintain it within this range for at least 10 seconds.
- Engine idling.
- Check error logs / Check readiness.

Setpoint Readiness (MWB 017.1): 00000000
Setpoint Readiness (MWB 017.2): 00000110
Setpoint Readiness (MWB 017.3): 10,000,000
Setpoint Readiness (MWB 017.4): 00000000

That should be it then.

Sebastian@OpenOBD wrote:

According to VAG, the entire process should proceed as follows at the ASZ.

Great, thank you... I'll try it out soon .

Is there a time limit for the idle phases?

ulf wrote:

Great, thank you... I'll try it out soon.

Sure, a report would be great.

ulf wrote:

By the way, is there a time limit for the idle phases?

As far as I can tell, no.

Sebastian@OpenOBD wrote:

ulf wrote: Great, thank you. . . I will try it out soon. Yep, a report would be nice.

Hi Sebastian,

I tried it. For the LL times, I also set a generous amount of time, more than 10 seconds each.
The water temperature initially measured 85°C (according to MWB 001.4), but I didn't continue to monitor it. However, the thermostat is working correctly, so the temperature shouldn't have dropped below 80°C.

In the first run, I kept the MWB 3 running to precisely control the speed and, incidentally, observe the EGR function.
Result: 00000000 / 01100110 / 10000000 / 10000000
so, like immediately after clearing the error memory = failure

In the second run, I let the MSG run completely unattended, meaning without any diagnostic prompts or interactions.
Result: 00000000 / 00000110 / 10000000 / 00000000 = Readiness code set


Based on my experience, the instructions should actually read:

- Ignition ON, Engine OFF.
- Read the readiness code (part number 017).
- Check and clear fault codes (clearing resets the readiness codes).
- Check the coolant temperature (e.g., MWB 001.4); it must be above 80°C.
- End the diagnosis dialog (close the message)

- Ignition OFF (for at least 6 seconds).
- Ignition ON, Engine ON.
- Run the engine at idle for at least 10 seconds.
- Increase the motor speed to 2450-2850 RPM and maintain this speed for at least 10 seconds.
- Run the engine at idle for at least 10 seconds.
- Increase the engine speed to 1600-1800 RPM and maintain this speed for at least 10 seconds.
- Run the engine at idle for at least 10 seconds.

- Check error logs / Check readiness.
Setpoint Readiness (MWB 017.1): 00000000
Setpoint Readiness (MWB 017.2): 00000110
Setpoint Readiness (MWB 017.3): 10000000
Setpoint Readiness (MWB 017.4): 00000000

These LL times are based solely on my successful attempt and may even be shorter.

The diagnosis "should" not affect the process, as the VAS 505x also retrieves measurement values during the procedure. Nevertheless, thank you for the feedback.

Sebastian@OpenOBD wrote:

The diagnosis "should" not affect the process, as the VAS 505x also retrieves measurement values during the procedure. Nevertheless, thank you for the feedback.

Well, the first time, I thought I had done everything right, but it still didn't work. Could it be that two attempts are necessary?

ulf wrote:

...could it be that 2 passes are necessary?

Actually, not really, as long as you stay within the specified RPM range and keep your foot still.

Nevertheless, I think 2 sets are still better than a tour around the block.

Mephisto wrote:

As far as I know, the inspector is running the engine at full throttle

so that the idle speed can be checked.
likely to ensure that the exhaust system is fully purged before the measurement.

It also tests the durability of the timing belt and the self-ignition/self-sufficiency feature that draws power from the oil pan.

I've already seen it - an incredible bang from the testing facility... then an old man runs out, then two people in blue uniforms run out... *BOOM* and then it's quiet again. And everything is filled with smoke... what a great ASU!

"By the way, who actually pays for this?"

Sebastian@OpenOBD wrote:

Nevertheless, I think 2 sets are still better than a tour around the block.

Yep... I'll try it again sometime soon. Maybe I'll have some more "aha!" moments then.
BTW: Other EOBD pilots are, of course, welcome to participate .

Quote:

A huge crash from the testing hall... then an old man runs out, then two people in blue run out... *BOOM* and then it's quiet again. And everything is filled with smoke... great, what an ASU!! btw. who actually pays for that?

You have three chances to guess.
A little hint: "Driver" and "asshole" start with the same letter...