P20E8: Reductant Pressure Too Low
8 vehicles · 8 makes · $150-$2,500 repair
Most Reported On
P20E8 is an OBD-II diagnostic trouble code meaning “Reductant Pressure Too Low.” P20E8 is a generic powertrain code that applies to diesel vehicles with a Selective Catalytic Reduction (SCR) emissions system, which injects diesel exhaust fluid (DEF, also sold as AdBlue) into the exhaust to convert smog-forming nitrogen oxides into harmless nitrogen and water. The engine control module sets this code when the DEF pump cannot build or hold the pressure the system needs (roughly 70-90 psi on most applications) to dose fluid accurately into the exhaust stream. Day to day you may notice little beyond a check engine light and a DEF or SCR warning message, though some vehicles show reduced power. Because SCR operation is emissions-mandated, ignoring the code typically starts a countdown to a derate: the vehicle will progressively limit speed (often to 55 mph, then as low as 5 mph on trucks) or refuse to restart until the fault is repaired. Some manufacturers word the same code as "DEF Pressure Too Low" or "SCR Urea Pressure Too Low," but the meaning is identical. This code is most commonly reported on 2016-2021 Volvo V60, 2022-2025 Mazda CX-60 (3.3 Diesel, e-Skyactiv D), and 2017-2023 Skoda Kodiaq, plus 5 other vehicles, with repair costs ranging from $150 to $2,500.
Common Causes
Typical Repair Cost
Based on 8 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
This is a powertrain code, so a basic OBD-II reader can read it. These read P20E8.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple code reader for engine (P) codes on many compatible OBD-II vehicles. It does not support every vehicle or hybrid/EV application, and it does NOT read body, chassis or network codes; confirm exact-vehicle compatibility before buying.
- Read & clear engine (P) codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth scanner with a companion app that reads beyond the engine module — ABS, SRS and transmission — plus manufacturer-specific codes on many vehicles.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X V3.0 Elite OBD-II Scanner
by LAUNCH
Handheld scanner covering the four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level tablet with all-system coverage and bi-directional control, so you can command a module rather than only read it.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
What you can do yourself, and what needs a shop
Reading the code, clearing it, and watching whether it returns is a driveway job with the right scanner. These steps are not:
- Module programming or software updates — needs the manufacturer software or a J2534 pass-through with a paid subscription.
- Replacing a control module — most are VIN-programmed and immobilizer-registered, so a new one does nothing until it is coded to your car.
- Airbag/SRS component work — a stored fault can deploy a live device.
If the vehicle is still under warranty, check for an open recall or technical service bulletin before buying anything — the repair may already be covered.
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Vehicles Affected (8)
FAQ
What does P20E8 mean?
P20E8 stands for "Reductant Pressure Too Low." P20E8 is a generic powertrain code that applies to diesel vehicles with a Selective Catalytic Reduction (SCR) emissions system, which injects diesel exhaust fluid (DEF, also sold as AdBlue) into the exhaust to convert smog-forming nitrogen oxides into harmless nitrogen and water. The engine control module sets this code when the DEF pump cannot build or hold the pressure the system needs (roughly 70-90 psi on most applications) to dose fluid accurately into the exhaust stream. Day to day you may notice little beyond a check engine light and a DEF or SCR warning message, though some vehicles show reduced power. Because SCR operation is emissions-mandated, ignoring the code typically starts a countdown to a derate: the vehicle will progressively limit speed (often to 55 mph, then as low as 5 mph on trucks) or refuse to restart until the fault is repaired. Some manufacturers word the same code as "DEF Pressure Too Low" or "SCR Urea Pressure Too Low," but the meaning is identical.
What are the most common causes of P20E8?
The most common causes of P20E8 are: Failed or weak DEF (reductant) pump that cannot build specified pressure, Clogged reductant pump filter cartridge — DEF crystals gumming the internal filter is the most common cause on Duramax and Power Stroke trucks, Contaminated, diluted, or crystallized DEF fluid (or DEF frozen in cold weather due to a failed heater), Leaking DEF supply lines or fittings, or a DEF injector stuck open and bleeding off pressure, Faulty reductant pressure sensor giving a false low reading, Damaged or corroded wiring/connectors to the DEF pump or pressure sensor, Low DEF tank level. The specific cause varies by vehicle.
How much does it cost to fix P20E8?
Repair costs for P20E8 range from $150 to $2,500, depending on the vehicle and root cause.
Which vehicles are affected by P20E8?
Au7o has documented P20E8 across 8 vehicle models from 8 manufacturers: Jeep, Mazda, Mercedes-Benz, Opel, Peugeot, Skoda, Volkswagen, Volvo.
Sources (12)
- ForumAdBlue system problem - Volvo Owners Forum
- articleAdBlue system errors when the NOx sensor does not work - NOx Sensor Expert
- ForumCX-60 and AdBlue issue - Mazda CX-70 Forum
- ForumAdblue system fault | Skoda Kodiaq SUV Forum
- ForumSkoda Kodiaq 2.0 TDI problems with DPF regeneration | MyCarly Community
- articleDPF warning light ON in Skoda Kodiaq. What to check? | DailyDriven
- ForumAdblue tank replacing and updating the ECU to accept the new tank and electrical components | Peugeot 208 Forums (208ownersclub)
- articlePeugeot & Citroen AdBlue failure fix (lists 208; P20E8/P20EE, urea light, countdown) — Torx Tuning
- articlePeugeot AdBlue Fault Fixed (208 BlueHDi listed; P20E8, pump/PCB failure, non-start) — Fastlane Performance
- articleAdBlue: l'UFC-Que Choisir saisit la DGCCRF et la Commission europeenne (Peugeot/Citroen most affected, 1,731 testimonies, ~EUR 1,000 avg repair)
- ForumAdBlue Fault, no start countdown — Club Touareg Forum
- ForumAdBlue Sensor Malfunctions — Club Touareg Forum
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.