Cold Start SCR NOx Catalyst Inlet Temperature Too Low

Common symptoms

What you'll notice

• Check the coolant level and ensure it is at the recommended level for optimal temperature.
• Inspect the thermostat and replace if necessary to ensure proper engine temperature.
• Clean or replace the intake air temperature sensor to improve temperature readings.
• Check for any exhaust leaks or blockages that could be affecting the temperature in the SCR NOx catalyst inlet.
• Update the engine control module software to ensure accurate temperature regulation.

Common causes

Most likely first

1. Cold weather or low ambient temperature
2. Engine not reaching operating temperature
3. Malfunctioning thermostat
4. Faulty or clogged coolant system
5. Defective temperature sensor

How to diagnose & fix

Work through it in order

1. Difficulty starting the vehicle when the engine is cold
2. Reduced engine power or lack of response to accelerator pedal
3. Poor fuel efficiency or decreased miles per gallon (MPG)
4. Increased exhaust emissions, including black smoke from the tailpipe
5. Malfunction Indicator Lamp (MIL) or Check Engine Light illuminated on the dashboard