P20EE
PPowertrainSCR NOx Catalyst Efficiency Below Threshold (Bank 1)
What does this code mean?
Severity : MediumP20EE indicates that SCR NOx catalyst efficiency on bank 1 is below the expected threshold. The ECU compares readings from the NOx sensors before and after the catalyst and finds that nitrogen oxides are not being reduced enough. AdBlue quality, dosing or the catalyst itself may be at fault.
Symptoms
- Check engine or AdBlue warning light on.
- Warning message with a countdown before engine start is restricted.
- Possible power reduction depending on the vehicle.
- Often no drivability symptom.
Possible causes
- Poor quality, diluted or contaminated AdBlue/DEF.
- AdBlue injector crystallised or partially blocked.
- Faulty upstream or downstream NOx sensor.
- Low AdBlue pressure from the pump or a leak.
- Fouled or aged SCR catalyst.
- Exhaust leak distorting NOx readings.
Diagnosis and repair
- Check AdBlue level and quality, for example with a refractometer.
- Check NOx sensor readings in live data.
- Run an AdBlue injector dosing test with a diagnostic tool.
- Clean or replace the injector, NOx sensor or catalyst according to the diagnosis.
- Clear the code and road test to rerun the efficiency monitor.
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Code
P20EE
Category
Powertrain
Prefix
P
Standard
OBD-II / SAE J2012