PowertrainP0171
CautionSeverity: Caution - get it checked when you can
System Too Lean (Bank 1)
Key terms: Catalytic converter: cleans the exhaust gases · Oxygen sensor: measures oxygen in the exhaust gas · Mass air flow sensor: measures the air going into the engine · Bank 1: the side of the engine containing cylinder 1 · SAE J2012: the standard generic code list · Powertrain: engine, transmission and emissions
1What it means in plain English
The engine is running lean on one bank of cylinders. That means there is too much air or not enough fuel in the mixture.
2Common causes
- Vacuum or intake air leak
- Dirty or faulty mass air flow sensor
- Weak fuel pump or clogged fuel filter
- Leaking intake manifold gasket
- Faulty oxygen sensor
- Leaking fuel injector seals
3Can I drive?
Have it checked soon rather than ignoring it: a long-term lean mixture can overheat the engine and damage the catalytic converter.
This page gives general information. It is not professional advice. For a definite diagnosis and a repair quote, ask a qualified mechanic to inspect the car.
4Brand data 43
| Brand | Code | Description | System |
|---|---|---|---|
| Ashok Leyland CV | P0171 | Ambient Temperature Sensor Reading Struck In Range Or Sensor Failure Brand | Powertrain |
| BAIC Motor | P0171 | System Too Lean Bank 1 Brand | Powertrain |
| Mercedes-Benz | P0171 | System Too Lean (Bank 1) SAE | Powertrain |
| BMW | P0171 | Mixture too lean Brand | Powertrain |
| BYD | P0171 | Fuel system too lean Brand | Powertrain |
| Chery | P0171 | Fuel System Too Lean Brand | Powertrain |
| Chrysler | P0171 | Fuel system 1/1 rich control above limit Brand | Powertrain |
| Daewoo | P0171 | ECU EEPROM Error Brand | Powertrain |
| Daihatsu | P0171 | Lean abnormal Brand | Powertrain |
| DFFS | P0171 | Fuel too lean Brand | Powertrain |
| DFFX | P0171 | Fuel too thin Brand | Powertrain |
| DFXK | P0171 | Fuel system too lean Brand | Powertrain |
| EOBD | P0171 | System too lean bank 1 Brand | Powertrain |
| Ford | P0171 | System Too Lean (Bank 1) SAE | Powertrain |
| Geely | P0171 | B1 Fuel Trim Too Lean Brand | Powertrain |
| GM | P0171 | System Too Lean Bank 1 Brand | Powertrain |
| Great Wall | P0171 | System too lean Brand | Powertrain |
| Hafei | P0171 | System too lean Brand | Powertrain |
| Holden | P0171 | Fuel Trim System Lean Brand | Powertrain |
| Honda | P0171 | P0174 update Brand | Powertrain |
| Hyundai | P0171 | System Too Lean (Bank 1) SAE | Powertrain |
| Isuzu | P0171 | System Too Lean (Bank 1) SAE | Powertrain |
| Land Rover | P0171 | System Too Lean (Bank 1) SAE | Powertrain |
| Mahindra | P0171 | System Too Lean (Bank 1) SAE | Powertrain |
| Maserati | P0171 | System too lean (bank 1) Brand | Powertrain |
| Mazda | P0171 | System Too Lean (Bank 1) SAE | Powertrain |
| Mitsubishi | P0171 | Fuel trim too lean Brand | Powertrain |
| Nissan | P0171 | Fuel system - lean Brand | Powertrain |
| Opel | P0171 | System Too Lean Bank 1 Brand | Powertrain |
| Perodua | P0171 | Lean abnormal Brand | Powertrain |
| Peugeot | P0171 | System Too Lean (Bank 1) SAE | Powertrain |
| Porsche | P0171 | System Too Lean (Bank 1) SAE | Powertrain |
| Proton | P0171 | System Too Lean (Bank 1) SAE | Powertrain |
| Saab | P0171 | System Too Lean Bank 1 Brand | Powertrain |
| MG (SAIC) | P0171 | System Too Lean Brand | Powertrain |
| Smart | P0171 | System Too Lean (Bank 1) SAE | Powertrain |
| Sprinter | P0171 | System Too Lean (Bank 1) SAE | Powertrain |
| Subaru | P0171 | System Too Lean Brand | Powertrain |
| Suzuki | P0171 | Fuel system too lean (Bank 1) Brand | Powertrain |
| SWM Motor | P0171 | Mixing ratio too thin Brand | Powertrain |
| Tata | P0171 | Lambda Too Lean Brand | Powertrain |
| Toyota | P0171 | Fuel system too lean in non-idle condition Brand | Powertrain |
| Volkswagen | P0171 | Fuel Trim Brand | Powertrain |
Legend: SAE is the generic J2012 description; Brand is text taken from that manufacturer’s data. Manufacturer rows keep the wording and language of the source data, and non-English text is tagged so screen readers pronounce it correctly.
5Extended variant codes 13
These 7-character codes are manufacturer-specific variants of P0171 and may be reported by some scan tools.
| Brand | Code | Description | System |
|---|---|---|---|
| Mercedes-Benz | P017100 | Das Gemisch (Zylinderreihe 1) ist zu mager. Brand | Powertrain |
| SsangYong | P017100 | System too lean closed loop air/fuel ratio control at limit - system too lean Brand | Powertrain |
| Volvo | P017100 | If the values are less than 0.85 on bank 1, fault trace according to ECM Brand | Powertrain |
| SsangYong | P017101 | Bank #1 air/fuel ratio control malfunction - fuel rich Brand | Powertrain |
| SsangYong | P017102 | Bank #1 learning control malfunction - rich at idling Brand | Powertrain |
| SsangYong | P017103 | Bank #1 learning control malfunction - rich under low load Brand | Powertrain |
| SsangYong | P017104 | Bank #1 learning control malfunction - rich under high load Brand | Powertrain |
| SsangYong | P01710A | Insufficient MDP of injector #1(medium rail pressure) Brand | Powertrain |
| SsangYong | P01710C | Insufficient MDP of injector #4(medium rail pressure) Brand | Powertrain |
| SsangYong | P017110 | Bank #1 short-term learning control of air/fuel ratio: fuel rich Brand | Powertrain |
| SsangYong | P017114 | Insufficient MDP of injector #1(low rail pressure) Brand | Powertrain |
| SsangYong | P017116 | Insufficient MDP of injector #4(low rail pressure) Brand | Powertrain |
| Mercedes-Benz | P017184 | Das Gemisch (Zylinderreihe 1) ist zu mager. Es liegt ein Signal unterhalb des zulässigen Grenzwertes. Brand | Powertrain |
6Related codes
Browse Pxxx codes or P017xx codes.