P20EE on Skoda: How to Diagnose & Fix
SCR NOx Catalyst Efficiency Below Threshold
1 Skoda model · 1 documented issue · $250-$1,500 repair
P20EE on Skoda by model: symptoms, diagnosis and fix
Scala diesels (1.6 TDI, EA288) used mainly for short urban trips suffer DPF (diesel particulate filter) clogging because the exhaust rarely reaches the ~600 C needed for regeneration, so soot accumulates. Incomplete/interrupted regenerations also cause engine-oil dilution (diesel injected for regen washes into the sump), which can raise oil level and degrade lubrication. This is a VW-Group EA288 TDI pattern, the Scala included; Euro 6 cars can additionally see NOx-sensor and AdBlue/SCR injector crystallisation faults.
Common Symptoms
- DPF warning light
- Frequent regeneration
- Loss of power / limp mode
- Rising oil level / diesel smell in oil
- AdBlue or emissions warning
How to Fix
Take the car for a sustained motorway drive (20+ minutes at higher revs) to allow a full active regeneration; persistent blockage needs a forced regen or DPF clean/replacement. For city-only use, shorten oil-change intervals to manage dilution. Address AdBlue/NOx warnings by replacing the faulty NOx sensor or clearing/replacing a crystallised AdBlue injector. Read fault codes to confirm whether it is DPF, NOx sensor, or SCR.
What you need to diagnose it
The repair instructions explicitly call for reading stored codes. Use a scanner that can read the named code families before choosing a repair.The recommended scanner supports these code families; confirm your exact year, model and module coverage before buying.
ANCEL AD310 Classic OBD-II Scanner
Read & clear engine (P) codes
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Reading and clearing the code is DIY work. Module replacement or reprogramming is not — most modules are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.
Sources for this issue (2)
P20EE code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P20EE mean on a Skoda?
P20EE stands for "SCR NOx Catalyst Efficiency Below Threshold." This is a diesel emissions code meaning the Selective Catalytic Reduction (SCR) catalyst on Bank 1 is not cleaning up exhaust as well as it should. The SCR system sprays Diesel Exhaust Fluid (DEF) into the hot exhaust to convert harmful nitrogen oxides (NOx) into harmless nitrogen and water; NOx sensors before and after the catalyst tell the computer how well it is working. When the measured efficiency falls below the required threshold, this code sets. Because it is an emissions-protection code, it often triggers warning lights and can lead to reduced power or a speed limit (a 'derate') if left unfixed. On Skoda it is documented across 1 model: Scala.
What are the most common causes of P20EE?
The most common causes of P20EE are: Poor quality, contaminated, or wrong DEF fluid, Faulty or clogged DEF injector/dosing valve, Failed upstream or downstream NOx sensor, Degraded or failed SCR catalyst, Exhaust gas temperature sensor fault affecting dosing, Exhaust or DEF line leak, DEF line/heater problems (crystallization or freezing). The specific cause varies by vehicle.
How much does it cost to fix P20EE on a Skoda?
Published repair estimates on Skoda range from $250 to $1,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P20EE on a different make?
View P20EE across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.