OBD LensCatalyst system efficiency below threshold (Bank 1)
The engine controller has detected catalyst efficiency below its calibrated threshold on Bank 1.
- System
- Catalyst monitoring
- Vehicle match
- Unconfirmed
- Reference updated
- 29 Oct 2026
What this code tells you
The code alone does not establish which component needs replacement.
A code alone cannot confirm that driving is safe. If the lamp flashes, the engine runs badly or power drops, stop safely and seek qualified help.
What if a replacement converter did not resolve it?
Investigate the underlying engine condition with a technician. Replacing the converter again without identifying the reason for repeat failure can leave the problem unresolved.
Does the Subaru example apply to my car?
Not automatically. Subaru's August 2013 TechTIPS discusses repeat P0420 on higher-mileage vehicles and underlying engine issues. It is an example of why vehicle-specific diagnosis matters, not a repair instruction for every vehicle.
Preserve the diagnostic evidence
Save the complete scan, code status and freeze-frame data, together with symptoms and recent repairs, before any codes are cleared.
Full scan & code status
Stored, pending and permanent codes where available.
Freeze-frame data
The operating conditions recorded with the fault.
Symptoms & conditions
When it happens and how the vehicle behaves.
Recent repairs
Work performed before or after the code appeared.
Check the vehicle-specific guidance
Subaru technical newsletter; repeat P0420 on higher-mileage vehicles. Confirm applicability using current manufacturer information.
This manufacturer example supports the discussion above. It is not confirmation that the same procedure applies to your vehicle.
Find your vehicle’s diagnostic profileLibrary definitions and vehicle-reference families
BMW: P0420
Catalyst System Efficiency Below Threshold
- Reference namespace
- bmw
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Related catalog brands: BMW.
10 profiles assigned this reference family
Continental Synerject Easy U: P0420
Catalyst System Efficiency Below Threshold Bank 1
- Reference namespace
- continental-synerject-easy-u
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Ford: P0420
Catalyst System Efficiency Below Threshold (Bank 1)
- Reference namespace
- ford
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Related catalog brands: Ford.
28 profiles assigned this reference family
- 3.0L & 3.2L DieselFord
- Bronco 2021-Ford · 2021–onward
- EcoSport 1.6 Ztec 2009-Ford · 2009–onward
- Everest Gen.3 U704/UB (2022-n.d.) 3.0 Diesel + 10ATFord · 2022–onward
- Explorer 3.5 TiVCTFord
- Explorer Gen.6 3.0L (2020-n.d.)Ford · 2020–onward
- F150 VCTFord
- Falcon 4.0Ford · 2011–2014
- Focus II ST 2.5Ford
- Ford PHEV plug-in hybridFord
- Fusion 2.0 ecoboostFord
- Maverick 2022-n.d. 2.5 HybridFord · 2022–onward
- Mondeo Hybrid / Fusion HybridFord
- Mustang 2.3 EcoBoost (2015-2018)Ford · 2015–2018
- Mustang 2011 5.0 V8Ford · 2011–2011
- Mustang 2011-2017 3.7 V6Ford · 2011–2017
- Mustang GT 2016 5.0Ford · 2016–2016
- Mustang Mach-E (2023-)Ford · 2023–onward
- Mustang Mach-E / F-150 Lightning / E-TransitFord
- OBD-II / EOBD + CAN and extra PIDsFord
- OBDII/EOBD + SAE J1850 (Old Ford vehicles and trucks)Ford · 2004–2004
- Powerstroke 6.0L CANFord
- Powerstroke 6.4L CANFord
- Powerstroke 6.7L CANFord
4 more related profiles are listed in the vehicle directory.
Acura / Honda: P0420
Catalyst System Efficiency Below Threshold
- Reference namespace
- honda
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Related catalog brands: Honda, Acura.
12 profiles assigned this reference family
- Accord, Civic, CRV, CX-7 etc. 2008-2012 (var.1)Honda · 2008–2012
- Accord, Civic, CRV, CX-7 etc. 2008-2012 (var.2)Honda · 2008–2012
- Clarity PHEV, e:NY1Honda
- CR-V RE6, Accord DieselHonda
- EHonda
- Fit GK3Honda
- Honda/Acura HybridsAcura
- Insight II (2010-2014)Honda · 2010–2014
- OBD-II / EOBD + AT/CVT (CAN)Acura
- OBDII / EOBD GM based Ultium EV vehicles (2021-2025)Acura · 2021–2025
- OBDII / EOBD GM based Ultium EV vehicles (2026-n.d.)Acura · 2026–onward
- WWH-OBD (CAN 29 bit)Honda · 2026–2026
Genesis / Hyundai / Kia: P0420
Система катализатора, эффективность ниже порогового уровня (ряд 1)
- Reference namespace
- hyundai-kia
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Related catalog brands: Kia, Genesis, Hyundai.
401 profiles assigned this reference family
- OBD-II / EOBDHyundai
- OBD-II / EOBDGenesis
- Accent III / Verna MC 1.5 CRDI DieselHyundai
- Accent III MC / Verna 1.4/1.6 MPIHyundai
- Accent IV (RB/RC) / Verna / i25 / Excel III / Grand Pony 2010-2017 1.4/1.6 MPIHyundai · 2010–2017
- Accent IV RB 1.4/1.6 GDIHyundai
- Accent IV RB 1.6 CRDIHyundai
- Accent V / Verna HC 1.5 CRDI DieselHyundai
- Accent V / Verna HC 1.6 CRDI Diesel (2018-2022)Hyundai · 2018–2022
- Cadenza VG / K7 (2010-2016) 2.4 GDIKia · 2010–2016
- Cadenza VG / K7 (2011-2016) 2.7Kia · 2011–2016
- Cadenza VG / K7 (2011-2018) 3.0Kia · 2011–2018
- Cadenza VG / K7 (2011-2018) 3.0 LPIKia · 2011–2018
- Carens KY 1.5 CRDI Diesel (2021-n.d.)Kia · 2021–onward
- Carens/Rondo 2 UN (2006-2012) 2.0/2.4 MPI CANKia · 2006–2012
- Carens/Rondo 3 RP (2012-2021)Kia · 2012–2021
- Carens/Rondo 3 RP (2012-2021) 1.6 GDIKia · 2012–2021
- Carens/Rondo 3 RP (2013-2014) 1.7 CRDI Diesel TCIKia · 2013–2014
- Carens/Rondo 3 RP (2015-2021) 1.7 CRDI Diesel TCI-U2Kia · 2015–2021
- Carnival KA4 1.6 T-GDI HEV (2020-)Kia · 2020–onward
- Carnival KA4 2.2 CRDI Diesel (2020-)Kia · 2020–onward
- Carnival KA4 PE 2.0 T-GDI (2020-)Kia · 2020–onward
- Carnival KA4 PE 3.5 (2020-)Kia · 2020–onward
- Carnival/Sedona VQ-2 2.7 V6 (2006-2014)Kia · 2006–2014
377 more related profiles are listed in the vehicle directory.
ISUZU: P0420
Catalyst operating efficiency below threshold - Bank 1
- Reference namespace
- isuzu
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Related catalog brands: ISUZU.
1 profiles assigned this reference family
- D-Max gen. II (2012-2019)ISUZU · 2012–2019
Dodge / Mitsubishi: P0420
Catalyst System Efficiency Below Threshold (Bank 1); Catalyst deterioration
- Reference namespace
- mitsubishi
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Related catalog brands: Mitsubishi, Dodge.
31 profiles assigned this reference family
- ASX 2.2 ATMitsubishi
- Colt 1.3/1.5Mitsubishi
- Eclipse Cross 1.5T/2.0/2.4 + CVTMitsubishi
- Eclipse Cross 2.2 Diesel / Delica D5 (2019-) + 8ATMitsubishi · 2019–onward
- Eclipse Cross PHEVMitsubishi
- Galant 9 AT CANMitsubishi
- i-MiEVMitsubishi
- L200 / Triton Gen.6 (LC/MV) (2023-n.d.) 4N16Mitsubishi · 2023–onward
- L200 2.5 DI-DMitsubishi
- Lancer VIII 1.5/1.6 ATMitsubishi
- Lancer VIII 2.0/2.4 CVTMitsubishi
- Lancer VIII 2.0/2.4 SSTMitsubishi
- Mirage (2012-), Space Star, Dodge Attitude 1.2Dodge · 2012–onward
- OBD-II / EOBD + MUT-2 (K-LINE) (-2005)Mitsubishi · 2005–2005
- Outlander II 2.2 DI-DMitsubishi
- Outlander II, III 2.3 DI-DMitsubishi
- Outlander II, XL, III (3.0+AT)Mitsubishi
- Outlander IV 1.5T 4B40 (2022-)Mitsubishi · 2022–onward
- Outlander IV 2.5 PR25DD (2021-)Mitsubishi · 2021–onward
- Outlander PHEVMitsubishi
- Pajero IV 3.0, 3.8 V6 [EN]Mitsubishi
- Pajero IV 3.0, 3.8 V6 [RU]Mitsubishi
- Pajero IV 3.0, 3.8 V6 + AT V4A51 [EN]Mitsubishi
- Pajero IV 3.0, 3.8 V6 + AT V4A51 [RU]Mitsubishi
7 more related profiles are listed in the vehicle directory.
Infiniti / Nissan: P0420
Catalyst System Efficiency Below Threshold (Bank 1)
- Reference namespace
- nissan
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Related catalog brands: Nissan, Infiniti.
62 profiles assigned this reference family
- 370Z Z34 3.7 V6Nissan
- Almera G15 + ATNissan
- Altima 2013-Nissan · 2013–onward
- Altima L32 2.5Nissan
- Altima L32 3.5 V6Nissan
- Armada TA60 5.6 V8Nissan
- Frontier D40 2.5Nissan
- Frontier D40 4.0 V6Nissan
- Frontier D41 Gen.3 (2022-n.d.)Nissan · 2022–onward
- GT-R (R35)Nissan
- Juke 1.5dci K9K 636 [EN]Nissan
- Juke 1.5dci K9K 636 [RU]Nissan
- Juke 2014-Nissan · 2014–onward
- Juke F15 (2010-2018) 1.6 TURBO + CVTNissan · 2010–2018
- Kicks HP15 e-Power (Gen.1)Nissan
- Leaf ZE0/AZE0 (2010-2017)Nissan · 2010–2017
- Leaf ZE1 (2017-2025)Nissan · 2017–2025
- March/Micra K13 1.5Nissan
- March/Micra K13 1.6Nissan
- Maxima A35 3.5 V6Nissan
- Murano Z51 3.5 V6 + CVTNissan
- Murano Z52 2015-Nissan · 2015–onward
- Nissan Consult IIInfiniti · 2001–2008
- Nissan Consult II ABS ONLYInfiniti · 2001–2008
38 more related profiles are listed in the vehicle directory.
Generic OBD2: P0420
Catalytic converter system, bank 1 - efficiency below threshold
Слишком низкая производительность катализатора (bank 1)
- Reference namespace
- obd2
- Source revision
- legacy-2.2.20
Generic OBD2 definition; confirm the protocol and vehicle-specific service information.
Belgee / Geely / Proton: P0420
Catalyst System Efficiency Below Threshold (Bank 1)
- Reference namespace
- proton
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Related catalog brands: Belgee, Geely, Proton.
5 profiles assigned this reference family
Dacia / Renault: P0420
Низкая эффективность каталитической системы C-029
- Reference namespace
- renault
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Related catalog brands: Dacia, Renault.
170 profiles assigned this reference family
- Arkana, Kaptur, Duster II 1.3 TCe [EN]Dacia
- Arkana, Kaptur, Duster II 1.3 TCe [RU]Dacia
- Arkana/XM3 1.6 [EN]Dacia
- Arkana/XM3 1.6 [RU]Dacia
- Austral HybridRenault
- Captur 1.2Renault
- Captur 1.5 dCiRenault
- Captur II (HR16DEg3+PHEV)Renault
- Captur II 2019-/ Kadjar 2019- / Megane IV 2019- / Kangoo II 2019- / Duster II 2019- / Dokker 2019- / Lodgy 2019- / Logan II 2019- / Sandero II 2019- 1.5 dCi K9K 873 + AdBlueDacia · 2019–onward
- Clio 1.2 D4F 740 [EN]Renault
- Clio 1.2 D4F 740 [RU]Renault
- Clio III GT K4M 862Renault
- Clio III RS 2.0Renault
- Clio IV 0.9L H4BRenault
- Clio IV RS 200 EDCRenault
- Clio V 2019- / Captur II 2019- / Megane IV 2019-2024 / Kadjar 2019-2022 / Kangoo II 2019-2021 / Logan II 2019-2022 / Sandero II 2019-2022 / Sandero III 2020- / Duster II 2019- / Lodgy 2019- / Dokker 2019- 1.5 dCi K9K 872Dacia · 2019–onward
- Clio V H5H 1.3LRenault
- Clio-III 1.5 dCiRenault
- Clio-III 1.6Renault
- Clio-III 1.6 K4M 801 ECU S3000 + AT DP0 [EN]Renault
- Clio-III 1.6 K4M 801 ECU S3000 + AT DP0 [RU]Renault
- Dokker K7MRenault
- Dokker K9K 608, 612 [EN]Renault
- Dokker K9K 608, 612 [RU]Renault
146 more related profiles are listed in the vehicle directory.
GAC / Lexus / Toyota: P0420
Catalytic Converter System Bank 1 Efficiency Below Threshold
- Reference namespace
- toyota
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Related catalog brands: GAC, Toyota, Lexus.
24 profiles assigned this reference family
- OBD-II / EOBDLexus
- 29 bit EV data profileToyota
- BZ3XGAC
- Camry Hybrid XV50, RAV4 Hybrid 2016-2018, Auris TS HybridToyota · 2016–2018
- Corolla E110, E120 1CD-FTVToyota
- Corolla Hybrid 2020-, RAV4 Hybrid 2019-, Camry Hybrid 2018-, Avalon Hybrid 2019-Toyota · 2018–onward
- Corolla Verso / Avensis gen.2 (2004-2007) DieselToyota · 2004–2007
- GT-86 (2012-2021)Toyota · 2012–2021
- Highlander Hybrid Gen.3Toyota
- JOBD JDM CANLexus
- OBD-II / EOBD ~1999-2008 K-Line/KWP + extra sensorsLexus · 1999–2008
- OBD-II / EOBD ~2006-2009 CAN + extra sensorsLexus · 2006–2009
- OBD-II / EOBD ~2010-2022 CAN + extra sensorsLexus · 2010–2022
- OBD-II / EOBD ~2016 - n.d. CAN + extra sensorsLexus · 2016–onward
- Prius Gen. 2 (2004-2009)Toyota · 2004–2009
- Prius Gen. IV (2015-)Toyota · 2015–onward
- Prius Gen.3 2010-Toyota · 2010–onward
- Prius PrimeToyota
- RAV4 Prime PHEV (2019-2025), Prius Prime (2023-n.d.) / Lexus NX450h+ PHEVLexus · 2019–onward
- Tacoma gen.3 (2016-n.d.)Toyota · 2016–onward
- Vitz 2009 CVTToyota · 2009–2009
- WWH-OBD EV (CAN 29 bit) (2026-n.d.)Toyota · 2026–onward
- WWH-OBD HEV/PHEV (CAN 29 bit) (2026-n.d.)Toyota · 2026–onward
- WWH-OBD ICE (CAN 29 bit) (2026-n.d.)Toyota · 2026–onward
УАЗ: P0420
Эффективность нейтрализатора ниже допустимой нормы
- Reference namespace
- uaz
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Related catalog brands: УАЗ.
4 profiles assigned this reference family
Audi / Jetta / MAN / Seat / Skoda / Volkswagen: P0420
Catalyst System Low Efficiency
Catalyst System Low Efficiency
- Reference namespace
- vag
- Source revision
- legacy-oem-dtc-r2-20260924
Reference family assigned by the production catalog. An entry in this family is not proof of a fault or ECU support on every listed vehicle.
Related catalog brands: Skoda, Volkswagen, Audi, Seat, MAN, Jetta.
56 profiles assigned this reference family
- Amarok gen.1 (2010-2022) 2.0 TDIVolkswagen · 2010–2022
- Amarok gen.1 (2010-2022) 3.0 TDIVolkswagen · 2010–2022
- Caravelle 2.5 TDIVolkswagen
- Crafter NF 2016-2019, TGE 1 2.0 TDIMAN · 2016–2019
- EV: e-Golf (24 kWh) 2014-2016Volkswagen · 2014–2016
- EV: e-Golf (36 kWh) 2017-2021Volkswagen · 2017–2021
- EV: eTron 55Audi
- EV: e-UP! gen.2, Citigo E, Mii EV (32kWh)Seat · 2019–onward
- EV: e-Up!, CitiGo E, Mii EV gen.1Jetta
- MLB: 2.0 TSI/TFSI: CAEB, CDNC var.1Audi
- MLB: 2.0 TSI/TFSI: CAEB, CDNC var.2Audi
- MLB: 2.0 TSI/TFSI: CPMAAudi
- MLB: A5/S5 B8/8T (2007-2013) + ATAudi · 2007–2013
- MLB: Diesel DPF var.16 [EA896]Audi
- MLB: Diesel DPF var.6 [EA897]Audi · 2008–2016
- MLB: Diesel var.14 EA189 2.0 TDI (UDS ECM ONLY)Audi
- MLB: EA824 4.0 TFSI (CWUB, CWUC)Audi · 2015–2018
- MLB-EVO: Diesel DPF var.12 [EA897 Evo 3.0TDI] (Audi: A4 8W, A5 8W, Q5 80A, Q7 4M, A8 4N, A7 4K8, A6 4K, Q8 4MN, VW Touareg CR)Audi
- MLB-EVO: Diesel DPF var.13 [EA288 Evo 2.0TDI] (Audi: A4 8W, A5 8W, Q5 80A, Q7 4M, A8 4N, A7 4K8, A6 4K, Q8 4MN, VW Touareg CR)Audi
- MLB-EVO: Diesel DPF var.15 [EA897 Evo3 3.0TDI]Audi
- MLB-EVO: Diesel DPF var.4 [EA288 2.0 TDI] (Audi: A4 8W, A5 8W, Q5 80A, Q7 4M, A8 4N, A7 4K8, A6 4K, Q8 4MN)Audi
- MLB-EVO: Diesel DPF var.5 [EA897 3.0TDI] (Audi: A4 8W, A5 8W, Q5 80A, Q7 4M, A8 4N, A7 4K8, A6 4K, Q8 4MN, VW Touareg CR)Audi
- MLB-EVO: Diesel DPF var.8 [EA897 Evo2 3.0TDI] (Audi: A4 8W, A5 8W, Q5 80A, Q7 4M, A8 4N, A7 4K8, A6 4K, Q8 4MN, VW Touareg CR)Audi
- MLB-EVO: Diesel DPF var.9 [EA897 gen.2 3.0TDI] (Audi: A4 8W, A5 8W, Q5 80A, Q7 4M, A8 4N, A7 4K8, A6 4K, Q8 4MN, VW Touareg CR)Audi
32 more related profiles are listed in the vehicle directory.