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Emissions & exhaust
DPF, EGR, AdBlue and SCR, NOx, catalysts and lambda sensors: the codes behind most warning lights on modern diesels.
69 real cases · Page 2 of 3
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Diagnosing Conflicting O2 Sensor Codes on a Maserati Levante
A 2016 Maserati Levante with P2272, P0157, and P2198 codes shows how conflicting rich and lean O2 sensor signals require structured diagnostic testing. -
Diagnosing P0130 on a 2002 BMW 3 (E46)
Explore a real diagnostic case for a 2002 BMW 3 Series (E46) with a P0130 fault code. Learn why oil contamination and E-box leaks cause sensor failures. -
Diagnosing a P0130 Code on a 2015 Honda CR-V
A complete diagnostic breakdown of a P0130 code on a 2015 Honda CR-V 1.6 i-DTEC, covering sensor element failure, harness degradation, and exhaust leaks. -
Diagnosing P0401 on a Speed-Restricted 2011 Audi A3
See how low-speed restrictions and reduced exhaust temperatures cause P0401 insufficient EGR flow codes on a 2011 Audi A3, and how to verify the root cause. -
Diagnosing a Restart-Triggered P20EE on a 2016 Ford Transit V
A Swedish workshop faced an intermittent AdBlue restart warning and a P20EE fault code on a 2016 Ford Transit V. Read the full diagnostic breakdown. -
Diagnosing P20EE and P242F on a Citroen Berlingo DV5 Engine
A step-by-step diagnostic breakdown of a 2020 Citroen Berlingo logging P20EE and P242F. Learn how DPF ash load and AdBlue crystallization interact. -
Diagnosing P219600 on a 2011 Audi A4 2.0 TDI
A detailed look at diagnosing a P219600 rich mixture code on a 2011 Audi A4 2.0 TDI, covering sensor failure, soot contamination, and mechanical faults. -
Diagnosing P23AD00 on a 2020 Audi A6
Step-by-step diagnostic breakdown for a P23AD00 NOx sensor heater fault on a 2020 Audi A6. Covers internal failure, wiring resistance, and ECM software. -
Diagnosing P20D4 on a 2001 Mercedes SL M113
Why a generic P20D4 code on a 2001 Mercedes SL M113 points to a load limit active state triggered by the MAF, MAP, or throttle body, not a diesel injector. -
Nissan Navara U0401: AdBlue Counter Reset Failure
A Nissan Navara D23 with a U0401 fault code and an AdBlue counter that will not reset requires looking beyond the fluid tank. Here is the diagnostic path. -
Diagnosing a Lone P2002 on a Skoda Octavia 1.6 TDI
A step-by-step guide to diagnosing a P2002 DPF efficiency code on a Skoda Octavia III 1.6 TDI, from drive cycle issues to cracked ceramic monoliths. -
Toyota RAV4 P0138 and P1578: Why an O2 Sensor Disables the 4x4
A 2009 Toyota RAV4 with P0138 and P1578 codes causes the 4x4 and VSC lights to illuminate. Learn why the ECM disables stability control for an O2 sensor fault. -
Volvo V70 EGR Circuit Faults and Heavy Smoke
Learn how to diagnose a smoking 2010 Volvo V70 with EGR codes P040100, P141200, and P140200 by tracing circuit faults, harness issues, and boost leaks. -
The P20EE00 Smoke Screen on a 2016 Volvo V90
A 2016 Volvo V90 sets a P20EE00 code and smokes heavily during DPF regeneration despite low soot. Explore the diagnostic path for this specific fault. -
Diagnosing a P0456 EVAP Leak on a 2013 Lexus LX570
A 2013 Lexus LX570 arrived with a P0456 very small EVAP leak code. See how we rank the fuel cap, vapor lines, and solenoids to speed up the diagnosis. -
Diagnosing P0497 and P0456 on a 2008 SAAB 9-3
A step-by-step look at diagnosing P0497 and P0456 codes on a 2008 SAAB 9-3 2.8L turbo, moving past the gas cap warning to find the real EVAP fault. -
Diagnosing P0299 and P0404 on a 2011 Hyundai i40
A diagnostic case study of a 2011 Hyundai i40 presenting with a sluggish engine and fault codes P0299 and P0404, exploring the link between EGR and underboost. -
Diagnosing a Fake EVAP Code on a Toyota Avensis Diesel
A generic scanner misread a P1443 code as an EVAP fault on a 2015 Toyota Avensis diesel. We break down the true DPF and EGR vacuum causes. -
P04AF00 and Blocked OPF Regeneration on the Audi Q8
How an active P04AF00 EVAP fault code on a 2020 Audi Q8 4.0 TFSI completely blocks particulate filter regeneration, and how to trace the root cause. -
Decoding a Multi-System Cascade on a 1.8 TSI
A step-by-step breakdown of how a 2009 SKODA Superb II with a 1.8 TSI engine triggers intake manifold, EVAP, and oxygen sensor faults simultaneously. -
Diagnosing P2196 on a 2006 MINI II: Stuck Rich or Lying Sensor?
Explore a real diagnostic case for a 2006 MINI II with a P2196 code. Learn why a torn PCV membrane on the N12B16A engine mimics a failed oxygen sensor. -
Diagnosing Shared Circuit Faults on a 2006 Opel Astra H
Learn how to diagnose P0135, P0141C, and P0443 on a 2006 Opel Astra H by tracing shared power circuits rather than replacing multiple parts at once. -
Diagnosing a Persistent P2002 on a 2019 Opel Insignia B
A broken intercooler hose on a 2019 Opel Insignia B triggered a persistent P2002 DPF code. Here is the exact diagnostic path to clear it. -
Peugeot 308 DPF Warning: When the EGR is the Real Fault
A 2010 Peugeot 308 presents with a DPF warning light, but fault codes P1490, P0401, and P0490 point to the EGR valve and cooling fan as the real culprits.