Hella 6PT 009 309-331 NTC 12V coolant temperature sensor (2-pin, sealed plug)

The essentials

If you’re chasing a coolant temperature fault, a coolant temperature sensor is one of the first components people look at. This Hella 6PT 009 309-331 is an NTC (negative temperature coefficient) sensor built for a plug-in install with two connections. On paper, it’s the sort of replacement part that’s meant to restore the readings your vehicle’s systems rely on, rather than add “tuning” or experimentation.

It’s also a sensible choice when you want the job to be as straightforward as possible: the description notes it comes with a seal and with a retaining ring, which can remove a bit of faff compared with sensor-only replacements.

That said, it’s still a part where correct vehicle match matters. The listing mentions fitting “for example VW Golf VI (5K1)” and advises to verify the exact application—so it’s not something to buy purely by general engine cooling layout.

What to know before you buy

The key details that influence whether this sensor will be the right one for your job are the type and the connection style:

• Sensor type: NTC
• Voltage rating: 12V
• Connections: 2
• Mounting type: plug-in (with seal)

In practical terms, that means you’re not looking at a one-off adaptor situation. This is designed to slot into the factory-style setup—assuming your existing sensor is the same type and uses the same plug configuration.

A small but important point: the listing includes colour correspondence to the original part (listed as grey/black), and also describes the sensor as black. Colour shouldn’t be your only matching factor, but it’s often a clue you’re dealing with the correct family of component.

Installation feel and everyday practicality

For many coolant temperature sensor replacements, the “make or break” is whether you can remove the old unit and plug in the replacement without breaking tabs or fighting corroded connectors. This one is described as plugged and includes the seal in the supply, which should help with getting a proper fit and avoiding the small leaks or moisture issues people sometimes see around poorly sealed sensor housings.

Also, because it notes technical assistance and free installation instructions via Hella Tech World, it’s worth considering if you prefer following manufacturer-style guidance rather than guessing torque or routing on your own.

If you’ve ever replaced a sensor where the connector sits awkwardly under engine bay heat shields, you’ll know how much a straightforward plug-in design can matter—even if the actual job is still fiddly.

Where it shines

This sensor makes the most sense when you:

• need a replacement coolant temperature sensor that matches the NTC type
• want a 2-pin, plug-in solution rather than adapting wiring
• appreciate having the seal included and a retaining ring to help secure it
• prefer parts from a well-known OEM-focused supplier for a straightforward repair

It’s a “get it working again” type of part. Not everything in vehicle diagnostics is glamorous, but coolant temperature signals are central, and having the right sensor type matters more than most people expect.

Things to watch (limitations)

The biggest limitation here isn’t the part itself—it’s the match. The listing says it fits applications such as a VW Golf VI (5K1) but stresses to verify the exact vehicle application. If your car doesn’t share the same sensor specification, you could end up with a sensor that physically resembles yours but doesn’t behave correctly in the ECU readings.

Also, the listing doesn’t provide broader compatibility tables or engine-by-engine details. That means you’ll likely need to check the part number against your vehicle’s existing sensor or the application information available through the manufacturer.

Tech specs (from the listing)

• Type: NTC
• Voltage: 12V
• Number of connections: 2
• Mounting type: plug-in
• Included: seal
• Included: retaining ring
• Item complement / extra info: with seal, with added mounting material
• Colour: black / corresponds to original grey/black

Mini FAQ

Is this sensor sealed, or will I need to reuse an old gasket?

The listing says the seal is included in the supply, which is one less thing to worry about.

How do I confirm it’s the right one for my car?

Use the guidance in the listing to verify the exact vehicle application (it gives an example of VW Golf VI (5K1), but that’s not a blanket guarantee).

What does “NTC” mean for coolant temperature sensors?

NTC refers to how the sensor’s resistance changes with temperature. The listing explicitly states this sensor is NTC, so matching that spec is important.

Is it a plug-and-play style replacement?

The mounting type is described as plugged and it has 2 connections, so it’s intended to connect via the corresponding connector rather than requiring major wiring work.

Final verdict

It’s a solid pick if you’re replacing a 12V, NTC, two-pin coolant temperature sensor and you want a plug-in part that includes the seal and retaining ring. If you don’t have a confirmed match for your exact vehicle/application, you may want to pause—this is one of those parts where buying “close enough” can lead to more diagnostic hassle than it saves.