⚠️ Critical Severity
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Complete SCR system deactivation → Pollutant emissions exceeding standards
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Risk of SCR catalyst deterioration (high cost)
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Engine power limitation (limp mode)
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Illegal to drive (imminent technical inspection failure)
🚨 Symptoms
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Excessive black smoke during acceleration
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Noticeable power loss (especially on inclines)
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Antipollution fault warning light illuminated (⛽ + 💨)
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Engine overheating (inappropriate gear ratios)
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Related fault code(s): P20BD, P2201
🔧 Common Causes (Probability Order)
| Rank | Cause | Details |
|---|---|---|
| 1 | Faulty reductant injector | Failed coil, clogged nozzles (DEF crystals) |
| 2 | Electrical issues | Damaged wiring, corroded connectors (moisture) |
| 3 | Insufficient DEF level/quality | Expired DEF, dilution, winter freezing |
| 4 | SCR module failure | PCM software error, failed NOx sensor |
| 5 | Contaminated DEF tank | Water, fuel, or impurities |
🔍 Diagnostic Procedure
Step 1: Initial Checks (15 min)
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DEF Level:
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Refill if < ⅓ (⚠️ use ISO 22241 certified DEF).
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DEF Condition:
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Drop on hot surface → must evaporate without residue.
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Visual Inspection:
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Injector (under exhaust line): leaks, white crystals.
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Connector: green corrosion (critical point on RAM 1500, VW TDI).
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Step 2: Electrical Tests
| Test | Tool | Normal Values |
|---|---|---|
| Injector resistance | Multimeter Ω | 10-15 Ω (20°C) |
| PCM voltage | DC Multimeter (ignition ON) | 12V on power wire |
| Injector activation | Specific scanner (e.g., Delphi, Bosch) | Frequency 1-10 Hz |
Step 3: Advanced Diagnostics
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Use a scanner capable of forcing the injector:
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Listen for injector click.
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Check DEF flow rate (PID data).
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Check DEF system pressure (failed pump?).
💰 Repairs & Costs
| Problem | Solution | Average Cost |
|---|---|---|
| Faulty injector | Replacement | 200-500 € |
| DEF circuit cleaning | System flush | 150-300 € |
| Damaged wiring | Harness repair | 100-250 € |
| SCR/PCM module | Reprogramming/replacement | 400-1200 € |
| Contaminated tank | Replacement | 800-1500 € |
⏱️ Service time: 1h (diagnostics) + 2h to 4h (repair).
⚠️ Consequences of Ignoring
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SCR catalyst blockage (replacement > 2000 €).
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Legal penalties:
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Fine up to 750 € (EU)
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Vehicle immobilization (technical inspection).
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Turbo overheating (excessive exhaust temperatures).
🔧 Pro Tips
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Winter emergency:
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Use DEF with antifreeze additive (e.g., AdBlue Arctic).
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Quick test:
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Disconnect injector → If code changes from P2058 to P2059, injector is faulty.
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Reset:
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After repair: reset DEF counter via scanner + forced regeneration cycle.
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Manufacturer references:
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Bosch injector 0 986 455 008 (VAG)
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Delphi SCR module 104843-11 (Ford)
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Known TSBs:
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RAM #18-047-20: Software update for false P2058 on 2019 EcoDiesel.
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📊 Workshop Statistics: 60% of P2058 resolved by injector replacement + DEF circuit purge.
Conclusion:
P2058 is a major antipollution failure. Recommended procedure:
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Check DEF level/quality
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Test injector resistance + PCM voltage
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Replace injector if faulty → Purge the circuit
Immediate intervention required: A deactivated SCR system can damage DPF and turbo in under 1000 km!