P20EE P204F P208B Audi 3.0 TDI – AdBlue Pump Pressure & SCR Catalytic Efficiency

Diagnostic Priority: High

Complexity Level: Advanced

Diagnostic guide for P20EE, P204F, and P208B on Audi 3.0 TDI V6. Reductant supply pressure loss, delivery pump failure, and start-lockout warnings.

Vehicle

AUDI

Codes

3 units

Analysis Type

Technical Expert

Status

Analyzed

Technical Analysis

REF: #4931D4

The combination of P20EE, P204F, and P208B indicates that the AdBlue reductant delivery pump cannot maintain specified rail pressure (4.5–6.0 bar), triggering SCR catalyst efficiency failure and engine restart countdowns.

Expected Symptoms

Glow plug light flashing and DPF icon illuminated on instrument cluster on AUDI (DTCs: P20EE, P204F, P208B)

Engine enters limp home mode restricting engine output above 2,200 RPM

Acrid exhaust odor and elevated fuel consumption due to aborted DPF regenerations

System Impact

Drivetrain

Engine Control

Emission Control

Potential Fault Sources

01Defective differential pressure sensor G450 or split silicone sample lines (affecting AUDI subsystem for P20EE, P204F, P208B)

02Severe soot loading in DPF caused by short-trip driving and fouled injectors

03Sticking EGR cooler changeover flap or faulty exhaust gas temp sensor G235 (logged fault: P20EE)

Workflow / Methodology

Verify supply voltage and sensor telemetry for P20EE, P204F, P208B on AUDI with multimeter at key ON.

Check DPF differential pressure with key ON: must read precisely 0 hPa (0.48–0.52 V).

Query calculated soot mass and oil ash volume in ECM live data blocks.

Execute service regeneration cycle under load following sensor replacement.

Live Data & Mätvärdestoleranser (Är/Bör-värden)

Fabriksgodkända referensvärden vid diagnos och live-avläsning

Mätvärdesblock

Parameter / Signal	Testvillkor	Bör-värde (Normalt)	Avvikelse / Varning
AdBlue Matartryck	Pump aktiv under drift	4.5 – 6.0 bar	< 4.0 bar (Tryckfall/Pumpfel)
NOx-sensor uppströms (G295)	Normal landsvägslast	150 – 600 ppm	Fastfruset 0 ppm el >1200 ppm
NOx-sensor nedströms (G687)	Varm SCR-katalysator (>220°C)	< 50 ppm	> 120 ppm (Otillräcklig rening)

Assessment & Action Proposal

Technical Recommendation

Install a new genuine AdBlue delivery pump module, reset SCR restart inhibitor counter in the ECU, and clear DTCs.

Need a deeper analysis? Use our advanced fault code analyzer to find likely connections and in-depth guidance.

Start Fault Code Analyzer

Vanliga frågor om dessa felkoder

Vad är den primära orsaken till felkoderna?

Kan man köra vidare med tänd motorlampa / varningslampa?

Körning med aktiva felkoder kan leda till strypt motoreffekt (nödläge / Limp Home), blockerad partikelfilterregenerering eller följdskador på mekaniska komponenter. Felsökning bör genomföras omgående.

Hur åtgärdas kombinationen på säkrast sätt?

Install a new genuine AdBlue delivery pump module, reset SCR restart inhibitor counter in the ECU, and clear DTCs.