VW Coolant Temperature Sensor - Rein 6U0919501B

Product Information

The engine coolant temperature (ECT) sensor, or simply coolant temp sensor, plays a vital role in monitoring the engine's operating temperature and communicating this information to various vehicle systems. This sensor is located in the engine's coolant passage typically in the cylinder head or block. It works by varying its resistance based on the temperature: as the engine heats up, the resistance decreases, and as it cools down, the resistance increases. The ECT sensor sends this data to the ECU, which uses it for several critical functions, such as the air-fuel mixture, ignition timing, and control of the cooling fans and dashboard temperature gauge. There are many European applications where there is more than one coolant temp sensor, separating the signals used for engine ECU and other functions such as gauges and fans.

A faulty sensor might send incorrect temperature readings to the ECU, resulting in poor engine performance. The most common example is if the sensor incorrectly signals that the engine is colder than it is, the ECU will enrich the air-fuel mixture unnecessarily, leading to rough idling, poor fuel economy, or even black smoke from the exhaust due to unburnt fuel.

Conversely, if the sensor falsely indicates an engine overheating condition, the ECU might trigger warning lights, prematurely activate the cooling fans, or even cause the car to go into "limp mode," limiting engine power to prevent damage (however this is a rarer failure mode).

• Wrong Temp Readings: If the coolant temperature gauge is acting unpredictably, or reading consistently too high or too low, it may be either a coolant temperature sensor or a thermostat. Because of this, it’s common to replace both of these parts at the same time for the best probability of success while the cooling system is opened.
• Running too rich: If you have noticed the temperature gauge is low and the exhaust is black and sooty, the engine might be stuck in the warm-up loop due to a bad coolant temperature sensor even though the engine is at the proper operating temperature controlled by the thermostat.
• Non-linear or suspicious live data output: For vehicles equipped with OBDII, use a scan tool to monitor the exact temperatures being output from the sensor. As the car warms up the output should be smooth and linear. If there are dead spots or it acts suspiciously, you may need to replace the sensor.

About Rein

Founded in 2007, CRP Automotive introduced the Rein Automotive line of OE-quality replacement parts to the aftermarket. And in just two short years, Rein Automotive has become very popular among both warehouse distributors and professional repair technicians. Rein is the German word for “pure”, and has come to be synonymous with quality in the automotive aftermarket. A true dealer alternative.

The Rein brand includes a growing number of “better than OE” parts for selected applications. These parts address known weaknesses and premature failures of factory parts. Many of these replacement and service solutions have been developed with the help of our Innovation Council, a hand-picked group of experienced professional repair technicians and shop owners throughout North America.

All Rein Automotive OE-quality parts are backed by the CRP Automotive standard, and are backed with a ISO 9001:2015 quality management system certification. Each year, CRP Automotive ships thousands of Rein Automotive brand products. And with widespread NAFTA market distribution through strategically placed warehouses in Cranbury, New Jersey and Puebla, Mexico - OE-quality products like Rein Automotive are delivered to customers both faster and more cost-effectively than ever before.

In 2017 Rein partnered with FCP Euro in competing a W204 C300 AER car for the 2017 season. The partnership focused FCP Euro to dive deep into the Rein catalog offering, and hundreds of new products were added and integrated into our catalog. Hundreds of new packages were created not only using the full part pine up of Rein products, but also the entire family of CRP products like Pentosin.

Rein is also an innovative brand, winning numerous trade awards — including multiple new product innovation awards at the annual AAPEX trade show.