P20EE — SCR NOx Catalyst Efficiency Below Threshold (Bank 1)
Category: Powertrain Severity: Medium
Updated:
DTC code P20EE means: SCR NOx Catalyst Efficiency Below Threshold (Bank 1). It falls under the "Powertrain" category, with an estimated severity of Medium. Common causes include poor-quality or contaminated DEF/AdBlue, dEF injector clogged with crystals and failed NOx sensor; it's worth confirming the diagnosis before replacing parts.
Possible causes
- Poor-quality or contaminated DEF/AdBlue
- DEF injector clogged with crystals
- Failed NOx sensor
- Deteriorated SCR catalyst
- Exhaust leak
Symptoms
- Engine or DEF warning light
- Countdown to no-start
- Loss of power
How to diagnose it step by step
- Check DEF quality.
- Inspect the DEF injector.
- Run a dosing test with a scan tool.
- Check the NOx sensors.
- Evaluate the SCR catalyst.
How to fix it
Check DEF quality (refractometer), clean the DEF injector and verify the NOx sensors before replacing the SCR catalyst.
Estimated repair cost
DEF: $15–40. Injector: $200–500. NOx sensor: $300–800. SCR catalyst: $1,500–4,000.
Frequently asked questions
What does DTC code P20EE mean?
SCR NOx Catalyst Efficiency Below Threshold (Bank 1).
Is code P20EE serious?
Severity Medium. Not urgent, but worth diagnosing to avoid bigger damage.
Can I keep driving with code P20EE?
You can drive, but watch the countdown: at zero the vehicle may not restart.
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