OBD LensSystem too lean (Bank 1)
The controller has detected a lean condition on Bank 1.
- System
- Fuel and air
- Vehicle match
- Unconfirmed
- Reference updated
- 29 Oct 2026
What this code tells you
A fault code is a diagnostic starting point; it does not identify a failed oxygen sensor by itself.
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.
Why check for an intake leak?
Ford TSB 04-17-4 describes vacuum leaks as one explanation for lean codes on its listed vehicles. Replacing sensors does not resolve an actual air leak.
What information helps the technician?
Bring the symptoms, repair history and stored data. Ford's bulletin uses fuel-correction comparisons under defined conditions; its thresholds and procedure must not be applied universally.
Preserve the diagnostic evidence
Keep the scan, freeze frame and available fuel-trim data before clearing codes. Note whether the problem occurs at idle, after warm-up or under load.
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
Selected Ford, Lincoln and Mercury vehicles listed in the August 13, 2004 bulletin; not every vehicle with P0171.
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: P0171
System Too Lean
- 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: P0171
System Too Lean 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: P0171
System Too Lean (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: P0171
Fuel System Too Lean
- 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: P0171
Слишком бедная смесь (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: P0171
System too lean - 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
Datsun / Lada: P0171
Система топливоподачи слишком бедная
Система слишком бедная
- Reference namespace
- lada
- 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: Lada, Datsun.
23 profiles assigned this reference family
- Bosch MP7.0Lada
- Granta / Mi-Do / On-Do + АКПП JatcoDatsun
- Largus (M86)Lada
- Largus 1.6 K4M (CAN)Lada
- Largus 1.6 K4M (К-Линия) 1.6 K4M (EMS 3132)Lada
- M74 CAN, ME17.9.7 CANLada
- M74/M75/Bosch 17.9.7Lada
- M75 CANLada
- Vesta (H4M+CVT, все блоки) 2019-2022Lada · 2019–2022
- Vesta (M86, все блоки) 2015-2022Lada · 2015–2022
- Vesta NG / Iskra + OBDII 2024- (M74.9 CAN)Lada · 2024–2025
- Vesta NG 2023- (M74.9 CAN), Niva Travel 2022-, Granta 2023- (M74.8, M74.9 CAN)Lada · 2022–onward
- Vesta, X-Ray (M86) без поддержки OBDII (2015-2022)Lada · 2015–2022
- X-Ray (M86) OBDII (двигатели ВАЗ, кроме Renault/Nissan)Lada
- X-RAY (OBDII+доп блоки)Lada
- X-Ray 1.6 H4M + CVTLada
- Итэлма М73Lada
- Итэлма М73 (вариант 2)Lada
- Итэлма М73, Bosch 7.9.7Lada
- Январь 5.1.1Lada
- Январь 5.1.1 (вар. 2)Lada
- Январь 7.2Lada
- Январь 7.2 (вар. 2)Lada
Dodge / Mitsubishi: P0171
System Too Lean (Bank 1); Fuel trim СЏtoo lean
- 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: P0171
System Too Lean (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: P0171
System too lean, bank 1
Смесь бедная (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: P0171
System Too Lean (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
GAC / Lexus / Toyota: P0171
Bank 1 System Too Lean
- 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: P0171
Система топливоподачи слишком «бедная» при ее максимальном обогащении
- 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: P0171
Fuel Trim System Lean Bank 1
Fuel Trim System Lean Bank 1
- 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.