An Independent Emissions Testing Lab recently tested the effects of a Webasto coolant heater on the emissions performance of a diesel engine. To simulate different temperature conditions during the seasonal changes and the effect caused by the Webasto heater, boundary conditions to the test engine were set at 40 degrees Fahrenheit and 75 degrees Fahrenheit during separate test runs. 

Emissions testing using an AC transient engine dynamometer, was performed to determine the effect of engine start-up temperature on PM, HC and CO emissions on a 2005 DT466 engine using an FTP Transient cycle with a Webasto Thermo Top C 5 Kw coolant heater (Part Number 923369). Emissions data shows that the start-up temperature has a significant effect on the engine emissions and overall performance of DPFs.

Results Summary:

  • Engine start-up temperature has a significant impact on the emissions levels emitted by the engine.*
  • PM emissions were reduced by 66 percent by pre-heating the engine during the cold weather conditions. Pre-heating also provided a 27 percent reduction in PM emissions during normal ambient conditions. This will help in longevity of the DPF life and can avoid more frequent regenerations and cleaning intervals.*
  • NOx emissions were reduced by around 40 percent by pre-heating the engine to 155 degrees Fahrenheit.*
  • The test results shows a 29 percent reduction in CO during winter conditions, and a 62 percent reduction during normal ambient conditions.*
  • Pre-heating the engine does not have a significant effect on the Hydrocarbon emissions.*

*Source:  ESW America Inc.  Results will vary based on engine size, duty cycle and overall maintenance.  FTP Cycles ran did not follow all the CFR testing requirements as test cell conditions were controlled to represent cold conditions. 

Webasto officials willingly share the results and state “The independent testing results show that 
pre-heating engines improves DPF performance and longevity along with extending the duration between cleaning cycles on engines that do not run a heavy duty cycle. Even engines in warm climates of 70 – 80 degrees Fahrenheit (for example) are not completely warm until they reach 
130 degrees Fahrenheit and higher for optimal performance.  Webasto coolant heaters provide optimal temperature at start-up.”


Webasto and ESW Group Form Strategic Partnership