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The X6 Odour of gas emanating from vents while in a stationary position


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I am seeking to use the extensive experience of BMW lovers to guide me on the correct path.

In June 2023, my spouse acquired a brand new BMW X6 3.0d Auto from the showroom.

Lately, we have observed the presence of a gas-like smell emanating from the internal vents on the dashboard, but only under certain circumstances.
The term "gas type odour" refers to the distinct scent that is intentionally added to home gas as a safety measure, allowing anyone to detect the presence of a gas leak.

The automobile has been returned to the dealership on two occasions, and it seems that although mainstream dealerships are capable of providing maintenance services and using computer diagnostics to identify flaws, they are no longer able to effectively troubleshoot and identify the specific issues.

Below is a sequential enumeration of actions that may be followed to replicate the issue.

1. It seems that the engine requires reaching its optimal temperature (which may be achieved by driving around 10 miles in the morning).
2. The automobile is now operating in Comfort mode, however there have been instances when it has occurred in Eco Pro mode.
3. There are no issues while the engine is operating.
4. The engine automatically shuts off when the automobile comes to a complete stop (Start Stop capability).
5. The change in functioning of the ventilation system may be perceived, presumably as a result of the engine being turned off and all operations being powered by the battery.
6. Approximately 5 seconds after coming to a complete stop, a scent of gas emanates from the vents.

Additional points:

1. In the air re-circulation mode of the ventilation system, there is no odour as the air within the cabin is being reused.
2. During my attempt to recreate the issue, I observed that the following factors amplify its visibility:

a) Activate the ventilation system's re-circulation mode prior to coming to a complete stop.
b) Await the cessation of engine operation via the use of the start-stop feature.
b) Deactivate the ventilation re-circulation mode, and you will immediately notice a stronger odour within a few seconds.

When I drove the vehicle to the dealership last week, I consistently recreated the smell by following the methods mentioned above. Both my wife and I stepped out of the car at the dealership and it seemed like we were starting to get a chest cold.

I am curious if anybody has seen similar problems or can recommend replacement components.
I will likely have to visit the dealership and incur expenses for them to repair the faulty components in order to see whether it resolves the issue. whether this course of action proves unsuccessful, it may be necessary to consider purchasing a vehicle from a different manufacturer.

Thank you in advance. I would certainly appreciate any thoughts or help.

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Here's an update after extensive research on Google.

Discovered a post on bimmerpost.com and came across a remark made by a member:

Therefore, I am now contemplating if the correlation between the auto start stop feature and the issue is really a chance occurrence, and whether the movement of the automobile or the operation of the engine when stationary is concealing the problem.

I have encountered similar discussions where minor oil leaks originating from the rocker or valve cover gasket would drip onto the exhaust manifold and subsequently evaporate due to the high temperature. This specific piece of information aligns with the observation that the issue tends to manifest after a substantial drive of at least 10 miles, during which the exhaust system becomes considerably heated.

I apologise for my lack of knowledge, I acknowledge that my use of terms may be inaccurate.

Today, I will bring the car to a nearby mechanic to request the removal of the engine cover and conduct a visual examination of the engine for any leaks.

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In my opinion, I do not believe that the rocker cover gasket is the cause of the issue. I have encountered a problem with my M135i where there is a distinct smell of burning oil, rather than petrol. Considering the relatively recent manufacturing year of your automobile, 2022, the potential cause of the issue you mentioned might be a leakage originating from the manifold or the junction point where the catalytic converter connects to the downpipe.

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I brought my X6 to an independent shop for inspection. They dedicated many hours to thoroughly examine the vehicle but were unable to identify any readily apparent issues. Given the car's recent manufacturing, they hesitated to disassemble the engine for further investigation.
Nevertheless, all the mechanics/technicians at the location unanimously acknowledged the presence of a vehicle issue and strongly advised against driving it, since the exact nature of the stench remains unknown.
In addition, they reached out to another BMW Dealership, distinct from our local one, and articulated their worries. Subsequently, the dealership expressed a desire for me to establish direct communication with them.
Upon consulting with the dealership, they recommended contacting BMW Assist as it would accelerate the automobile inspection process.

The BMW Assist representative arrived, verified the presence of an odour, and proceeded to contact a colleague by telephone. His coworker was knowledgeable of many new X6 BMWs that had a defective gasket on the turbo, resulting in leakage. He instructed me to accelerate the vehicle while he positioned himself under the hood and detected a faint odour emanating from the engine compartment. After seeing this discussion, he recommended that I emphasise the idea below about the leak in the down pipe.


The vehicle is now being transported to our recently established BMW Dealership for additional examination.

I inquired about the potential issue with the catalytic converter. However, it seems that these vehicles are equipped with sensors both at the inlet and outlet of the catalytic converter. Any malfunction would be promptly identified by the diagnostic system.

Observing a mechanic/technician engaging in fault detection brought back memories of my time in the RAF.

Thank you for the assistance provided so far. I will continue to provide updates on this topic as I gather further information.

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It is important to have your catalytic converters (CATS) inspected. If the CATS are obstructed and releasing harmful substances into the cabin, it is crucial to avoid inhaling them. Additionally, if the CATS are leaking into the cabin, it is especially unsafe to have small children in the vehicle.

Arrange for a nearby automotive workshop to do an emissions test on the vehicle. This will provide insight into if there is a catalytic converter issue.

Obstructed catalytic converters emit an odour like sulphur or Mercaptan, which is a substance added to natural gas. The first indication of this scent would typically be detected via the ventilation system.

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Thank you everyone for your comments. I have scheduled an appointment with a local BMW expert today. I will print out all the feedback and ask them to thoroughly examine everything. I will provide the thread with the latest outcomes.

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After conducting a thorough examination and consulting with BMW technical experts, our new dealership has determined that the automobile is functioning according to expectations.

Consequently, we entered the sales department and successfully completed the transaction by selling the automobile to the dealership.

I am somewhat dissatisfied since the automobile was of high quality. However, I plan to return to purchasing Mercedes vehicles for my wife.

As Black Adder would say, Damn!

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