P20EE on Ford
SCR NOx Catalyst Efficiency Below Threshold
P20EE on Ford vehicles indicates scr nox catalyst efficiency below threshold. Au7o has documented this code across 2 Ford models — most commonly on F-250 Super Duty, Transit. 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. Typical repair costs on Ford range from $350 to $4,500, depending on the specific model and root cause.
Common Causes of P20EE
- •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)
P20EE on Ford by Model
Ford F-250 Super Duty(1 issue)
- 6.7L Power Stroke DEF/SCR System Failure - P207F and P20EE Codes2015-2022
The Selective Catalytic Reduction (SCR) system on 2015-2022 6.7L Power Stroke trucks - which uses Diesel Exhaust Fluid (DEF) to reduce NOx emissions - is prone to failure, most commonly triggering DTC codes P207F (Reductant Quality Performance) and P20EE (SCR NOx Catalyst Efficiency Below Threshold). Causes include degraded or crystallized DEF fluid (DEF has a shelf life of 1-2 years and degrades faster in heat), a failed DEF injector, SCR catalyst failure, DEF quality sensor failure, or NOx sensor failure. In limp mode, the truck's performance is severely limited. The system is complex and diagnosis requires a professional scan tool. The DEF injector is a particularly common failure point on 2017+ trucks.
Ford Transit(1 issue)
- NOx Sensor / SCR DEF System Faults Causing Reduced Power (2.0L EcoBlue Diesel)2018-2023
EcoBlue diesel Transits have documented owner reports of check engine lights and emissions system warnings related to SCR/DEF operation, commonly tied to NOx sensor faults or SCR efficiency monitoring. When the system detects persistent faults, it may trigger reduced power or countdown-to-no-start strategies depending on market/calibration. These issues are frequently accompanied by emissions-related DTCs and can be intermittent before becoming persistent.
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View P20EE across all makes →Frequently Asked Questions
What does P20EE mean on Ford?▼
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 Ford specifically, this code is documented across 2 models.
What causes P20EE on Ford vehicles?▼
Common causes on Ford: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P20EE on a Ford?▼
Repair costs on Ford range from $350 to $4,500, depending on the specific model and root cause.
Which Ford models have P20EE documented?▼
Au7o has documented P20EE on 2 Ford models: F-250 Super Duty, Transit.