Fuel Temp Sensor leak - diesel in ECU and harness

[Rainier Vermaak]

Dear forumites,

On the 4x4 Community a guy posted the following:

"My female friend in JHB drives a 2016 BMW 220D, 89000kms and serviced annually at BMW.

He car cut out recently and BMW towed it in stating the Fuel Temp sensor has a leak - quote to repair - R125 545 (includes an unrelated clamp for a brake line).

The attached video shows what needs to be replaced, as well as a parts list with prices."

The quote includes a wiring harness, DDE CO, turbo etc.

A bit of reading shows this is a weakness of the 2.0l diesel.

Should one do preventative maintenance and replace the sensor? My F34 is now on 240k km and runs like a watch.

 

[Rainier Vermaak]

Dear forumites,

On the 4x4 Community a guy posted the following:

"My female friend in JHB drives a 2016 BMW 220D, 89000kms and serviced annually at BMW.

He car cut out recently and BMW towed it in stating the Fuel Temp sensor has a leak - quote to repair - R125 545 (includes an unrelated clamp for a brake line).

The attached video shows what needs to be replaced, as well as a parts list with prices."

The quote includes a wiring harness, DDE CO, turbo etc.

A bit of reading shows this is a weakness of the 2.0l diesel.

Should one do preventative maintenance and replace the sensor? My F34 is now on 240k km and runs like a watch.

Is there anybody out there?

 

[MR_Y]

Is there anybody out there?

Ask Gemini or ChatGPT to summarise feedback on all forums from the internet.

From Gemini:

The fuel temperature/pressure sensor issue on the BMW B47 20d diesel engine is a known, though not universally common, problem that primarily surfaces in mid to higher mileage vehicles, often from around 50,000 km (30,000 miles) onwards.
Symptoms:
The issue manifests in two main ways:
* Direct Sensor Malfunction: Leading to symptoms like poor fuel economy, irregular temperature readings, black exhaust smoke, and the illumination of the Check Engine Light with relevant fault codes (e.g., P0183).
* Severe Fuel Ingress (more critical): A particular concern for the B47 20d is when the sensor's housing or seal fails, allowing diesel fuel to leak into the wiring harness. This fuel can then wick its way back to the Digital Diesel Electronics (DDE) control unit (ECU). This can lead to a range of more serious and often seemingly unrelated issues, including multiple and varied fault codes across different systems (e.g., air mass, boost, glow plugs), rough idling, stalling, a significant loss of power, hard starting, and visible diesel fuel contamination in electrical connectors, especially around the sensor or DDE itself.

Likelihood:
While not as widespread as common B47 issues like oil filter housing leaks, this sensor problem is a significant concern that has affected enough owners to be widely discussed in community forums. Its occurrence is best described as low to moderate, meaning it doesn't affect every vehicle, but it's a serious vulnerability that can lead to very costly repairs if it occurs, particularly due to potential DDE damage.

Mileage:
The issue tends to appear as a component of wear and tear, predominantly in mid to higher mileage vehicles. While a specific mileage is not guaranteed, reports often surface for vehicles from approximately 50,000 km (30,000 miles) and frequently above 100,000 km (60,000 miles). However, manufacturing defects could potentially cause earlier failure.

Here's an even more concise summary of fuel temperature sensor symptoms for the B47 engine:
Key Symptoms of a B47 Fuel Temperature Sensor Issue:
* Warning Light: Check Engine Light (CEL) on.
* Poor Fuel Economy: Vehicle using more fuel than usual.
* Performance Issues: Rough idling, reduced power, or black smoke from the exhaust.
* Starting Difficulty: Especially noticeable in extreme hot or cold weather.
In short: If your B47 has a CEL, is drinking more fuel, running rough, or struggling to start, the fuel temperature sensor could be the culprit.

 

[Rainier Vermaak]

Ask Gemini or ChatGPT to summarise feedback on all forums from the internet.

From Gemini:

The fuel temperature/pressure sensor issue on the BMW B47 20d diesel engine is a known, though not universally common, problem that primarily surfaces in mid to higher mileage vehicles, often from around 50,000 km (30,000 miles) onwards.
Symptoms:
The issue manifests in two main ways:
* Direct Sensor Malfunction: Leading to symptoms like poor fuel economy, irregular temperature readings, black exhaust smoke, and the illumination of the Check Engine Light with relevant fault codes (e.g., P0183).
* Severe Fuel Ingress (more critical): A particular concern for the B47 20d is when the sensor's housing or seal fails, allowing diesel fuel to leak into the wiring harness. This fuel can then wick its way back to the Digital Diesel Electronics (DDE) control unit (ECU). This can lead to a range of more serious and often seemingly unrelated issues, including multiple and varied fault codes across different systems (e.g., air mass, boost, glow plugs), rough idling, stalling, a significant loss of power, hard starting, and visible diesel fuel contamination in electrical connectors, especially around the sensor or DDE itself.

Likelihood:
While not as widespread as common B47 issues like oil filter housing leaks, this sensor problem is a significant concern that has affected enough owners to be widely discussed in community forums. Its occurrence is best described as low to moderate, meaning it doesn't affect every vehicle, but it's a serious vulnerability that can lead to very costly repairs if it occurs, particularly due to potential DDE damage.

Mileage:
The issue tends to appear as a component of wear and tear, predominantly in mid to higher mileage vehicles. While a specific mileage is not guaranteed, reports often surface for vehicles from approximately 50,000 km (30,000 miles) and frequently above 100,000 km (60,000 miles). However, manufacturing defects could potentially cause earlier failure.

Here's an even more concise summary of fuel temperature sensor symptoms for the B47 engine:
Key Symptoms of a B47 Fuel Temperature Sensor Issue:
* Warning Light: Check Engine Light (CEL) on.
* Poor Fuel Economy: Vehicle using more fuel than usual.
* Performance Issues: Rough idling, reduced power, or black smoke from the exhaust.
* Starting Difficulty: Especially noticeable in extreme hot or cold weather.
In short: If your B47 has a CEL, is drinking more fuel, running rough, or struggling to start, the fuel temperature sensor could be the culprit.

I will replace the sensor as preventative maintenance.

 

[FILV]

This seems to be common on the B48 built on the 2 series chassis, so the X1 F48, 2 series Active Tourer etc

Must be the third of fourth time iv heard of this issue on a car of this platform. Not sure if perhaps its due to the3 location due to the smaller space compared to a 3 series or X3 etc?

Never heard of it on the B48 on any other platform.

 

[hansi06]

I had the same problem on my 2017 X1 around 70 000km/6 year mark. There were no symptoms, and they picked it up while it was in for service. Fortunately, it was still under motorplan. I think they replaced the wiring harness and DDE.