Fuel and injectionGeneric OBD-II codeUrgency: Garage soon
Code P2191: mixture too lean under high load (bank 1)
P2191 means: too lean under high load (bank 1).[1][2][3] The control unit sees that the long-term fuel adjustment of bank 1, in the high-load zone, exceeds its limit. AutoDTCs cites as a reference around +25% sustained for about 90 seconds with the engine fully warm: the control unit has already added the maximum fuel it is allowed and still cannot correct the mixture.[1]
What code P2191 means
The control unit sees that the long-term fuel adjustment of bank 1, in the high-load zone, exceeds its limit. AutoDTCs cites as a reference around +25% sustained for about 90 seconds with the engine fully warm: the control unit has already added the maximum fuel it is allowed and still cannot correct the mixture.[1]
Unlike P0171, which covers a lean mixture across the whole operating range, P2191 points to a problem that appears when the demand for air and fuel is high: hills, hard acceleration, towing. Samarins describes the same effect for any lean mixture under load: less power, slow acceleration and knocking, especially uphill.[1][4]
P2193 is the same warning on bank 2. It is a generic code of the OBD-II standard (it starts with P2), with the same definition on any brand.[5][6][7]
Original definition (SAE J2012): System Too Lean at Higher Load Bank 1[1][2][3]
Codes from the same family
They indicate the same problem in a specific cylinder, bank or sensor. Causes, symptoms and diagnosis are those on this page.
Causes of P2191 and its family
From most to least likely, according to the sources.
- 1Weak fuel delivery under load: a failing pump, a blocked filter, restricted injectors or a faulty regulator.[1][2]
- 2Air entering after the mass airflow meter without being measured: cracked intake hose, loose clamp, vacuum or crankcase ventilation leak, manifold gasket.[1][2][4]
- 3Dirty or under-reading mass airflow meter, so the control unit requests too little fuel.[1][2][4]
- 4Low or unstable fuel pressure due to a faulty regulator or a partially blocked supply line.[1][2]
- 5Exhaust leak near the upstream sensor, or a contaminated sensor giving a false lean reading.[1]
- 6Dirty or faulty crankcase ventilation (PCV) valve.[2]
Symptoms
- Hesitation or jerking when accelerating hard or on hills, which eases with light throttle.[1][2]Jerking: faults that cause it
- Loss of power or a “flat” zone under load.[1][2][4]Less power: faults that cause it
- Engine fault warning light on, which may flash if misfires are caused by the lean mixture.[1][2]Engine warning light: faults that cause it
- Higher consumption, sometimes with juddering at steady speed.[1][2]Uses more fuel: faults that cause it
- Knocking (detonation) when accelerating, especially uphill.[1][4]Engine knock: faults that cause it
How to diagnose P2191
In order: from the most likely and cheapest to check to the most expensive.
- 1Read the stored and pending codes and the freeze frame data. Watch the short- and long-term fuel adjustments while raising revs and load, and note where the positive peaks occur and at what coolant temperature.[1]
- 2Measure the fuel pressure and compare it with the specification; check that it does not drop when demand increases and that it holds for a few minutes after switching the engine off.[1]
- 3Look for unmetered air with the engine warm: intake hose, clamps, throttle body and manifold gaskets, and vacuum and crankcase ventilation hoses. Watch the adjustments while pinching the ventilation hose or applying a leak detector, and check that the purge valve holds vacuum.[1]
- 4If the adjustment is close to zero at idle and rises with revs, Samarins associates it with the mass airflow meter, a blocked catalytic converter or low fuel pressure; if it is already high at idle and falls on acceleration, with a vacuum leak.[4]
- 5Compare the mass airflow meter's reading with the expected flow across the whole rev range, check whether the upstream sensor has silicone or oil on it, and look for exhaust leaks before the catalytic converter.[1]
- 6Check the injectors and the mechanical condition: a balance test or speed drop per injector and, if the engine has high mileage and the differences are large, a compression test. After repair, clear the code and repeat the test with the same load and temperature.[1]
Can I keep driving with P2191?
Garage soon
AutoDTCs rates it as moderate severity and warns that a lean mixture under load can cause misfires, knocking and heat damage to the pistons and the catalytic converter if the engine is worked hard for a long time. It recommends driving gently and repairing it soon; Samarins includes knocking uphill among the effects of a lean mixture.[1][4]
Parts related to code P2191
The parts that most often cause this code. The code points to the circuit, not always the part: diagnose before you buy.
Fuel pump
Injector
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Documented faults related to P2191
Known faults of specific engines and cars, with their repair cost, the affected years and their sources.
Fuel pump and high-pressure pump: the most serious faults by engine and car
- Critical severityFrequency: Common2.0 and 2.5 HybridLow-pressure fuel pump failure: loss of power and fire riskYes: a low-pressure fuel pump with a defective impeller (Denso) affects millions of Toyotas and Lexuses, including Corolla, C-HR, RAV4 and Camry models with these engines. It can cause loss of power or stalling, and in the EU there is also a risk of leaks and fire on 2018-2022 Corolla, C-HR and Auris models.
- High severityFrequency: CommonBMW N54/N55High-pressure fuel pump (HPFP) failureThe N54's high-pressure pump is one of its best-documented failures: most units will have had it replaced at some point. It warns of itself with long cranking and loss of power; the 2010 campaign was US-only.
- High severityFrequency: Common2.2/2.5 dCiInjection pump or injector failureThe 2.2 dCi's common rail injectors fail fairly often on the X-Trail and Almera, with cases of seizing and leaks; on the Almera with the older YD22DDT, the documented fault is in the injection pump electronics, not the injectors.
- High severityFrequency: CommonVW 2.0 TFSI EA113Wear of the high-pressure pump cam followerYes: the 2.0 TFSI EA113's high-pressure fuel pump is driven by the camshaft through a follower (tappet) that wears; if it wears through it can damage the pump or the camshaft, so it should be checked and replaced as a preventive measure.Repair (garage): €250–€900Appears at around 90,000 km
Mass airflow sensor: the most serious faults by engine and car
- High severityFrequency: Occasional2.0 DTI and 2.2 DTIVP44 injection pump and air mass meter failureGerman Wikipedia documents recurring failures of the Bosch VP44 injection pump and the air mass meter in the early years of this engine. An owner testimony for this engine describes the pump being replaced at 192,500 km, at a cost the owner calls «prohibitive».
- Low severityFrequency: CommonM111Mass air flow sensor failureYes: the M111 mass air flow sensor can fail with use and cause jerking or rough running. English-language Wikipedia documents it on the W210 E-Class, and a French owner survey of the SLK R170 names it as the most-cited fault on that model.
- Low severityFrequency: Common1.8 T 20vAir mass meter (MAF sensor) failureThe air mass meter (MAF sensor) fails fairly often on the 1.8T: on the 150 hp Audi A3 it appears in 3 of the 11 reports collected, and it is also documented on the 180 and 225 hp Audi TT. It causes hesitation and loss of power; it is fixed by replacing the sensor.
- Low severityFrequency: Common1.9 TDIDirty or faulty air flow meter on the 1.9 TDI (loss of power)The air flow meter is a known weak point of the 1.9 TDI: it gets dirty or gives wrong readings, and the control unit limits the engine, causing a sudden loss of power. It is cheap to fix and does not damage the engine.Repair (garage): €100–€300
Injectors: the most serious faults by engine and car
- High severityFrequency: Very frequentOM651Delphi piezo injector failure (220/250 CDI)Yes: 220 and 250 CDI models built between 2008 and 2011 had Delphi piezo injectors that were prone to failing and seizing in the cylinder head. Mercedes-Benz replaced them under warranty in 2009 and switched the 220 CDI to solenoid injectors from 2010-2011, but the 250 CDI kept them.Repair (garage): €3,600–€5,900
- High severityFrequency: CommonBMW N52 / N53N53 piezoelectric injector failureThe N53's piezoelectric direct injectors fail frequently and cause misfires, rough idle and limp mode; replacing them is expensive and they must be coded.
- High severityFrequency: CommonMZR-CDOil dilution from leaking injector seals and DPF regenerationsOn the 2.0 and 2.2 MZR-CD, injector seals that age badly and incomplete particulate filter regenerations on short journeys can let unburnt diesel into the sump, diluting the oil and leaving the engine with less lubrication.
- High severityFrequency: CommonOM642Wear and failure of the Bosch piezo injectorsThe OM642's Bosch piezo injectors can fail from around 150,000-200,000 km, especially with poor-quality diesel; they cannot be repaired, only replaced. Because it is a V engine, those on the rear bank are harder to reach, which pushes up labour costs.Repair: €4,500–€6,500
Lambda sensor: the most serious faults by engine and car
- Medium severityFrequency: Common1.3, 1.5 and 1.6 gasolina (serie M)Faulty catalytic converter and lambda sensors on the 2005-2010 Swift (engine warning light)On the 2005-2010 Swift the catalytic converter often fails at around 50,000 km according to gebrauchtwagenberater.de, and several 1.6 owners cite the lambda sensor. The warning is the engine light; on the Sport the catalytic converter is integrated with the manifold.
- Medium severityFrequency: Occasional1.2 8v FireSensor failures: lambda sensor and crankshaft position sensor (TDC)The 1.2 8v Fire can suffer sensor faults: the lambda sensor (warning light, rough running) and, in the Fiat Punto, the crankshaft position sensor (TDC sensor), linked to misfires. These are minority issues, but they recur across several models with this engine.
- Low severityFrequency: Common1.4 and 1.6 TU3/TU5Sensors that fail: lambda sensor and temperature sensorThe lambda sensor and the coolant temperature sensor are, along with the coils, the components most cited as faulty: they cause an unstable idle, the engine warning light coming on or a cooling fan that does not behave normally.Appears at around 25,000 km
- Low severityFrequency: Common2.0 and 2.4 VVT-iLambda sensor failure on the 1AZ-FE (RAV4 and Avensis 2.0 VVT-i)Lambda sensors are the part that fails most in the RAV4 2.0 VVTi testimonials (about 20 cases among 75 testimonials) and also appear in those for the Avensis 2.0 VVTi; it is a limited-cost fault, not an engine one.Appears at around 150,000 km
P2191 by make
Documented faults that can trigger P2191 in each make's engines and cars.
Frequently asked questions
What is the difference between P2191 and P0171?
P0171 describes a lean mixture on bank 1 across the whole operating range. P2191 is limited to the high-load zone, that is, moments when the demand for air and fuel is high, and that points towards fuel delivery (pump, filter, injectors) or a mass airflow meter reading too low.[1]
Can I keep driving with P2191?
AutoDTCs rates it as moderate severity and advises driving gently until it is repaired, because a lean mixture under load can end up damaging pistons and the catalytic converter if the engine is worked hard.[1][4]
How do I tell whether it is a fuel or an air problem?
The fuel adjustments give the clue. According to Samarins, a high adjustment at idle that falls on acceleration points to a vacuum leak, while one close to zero at idle that rises with revs points to the mass airflow meter, a blocked catalytic converter or low fuel pressure. Pressure and leak tests confirm it.[1][4]
And if the code is P2193?
It is the same problem on bank 2: mixture too lean under high load. It is diagnosed in the same way, by checking the adjustments and the fuel pressure.[5][6][7]
Will I pass the MOT with code P2191?
If the code has switched on the engine warning light, no: with that light on, the inspection records a serious defect, and on Euro 5 and Euro 6 cars the ITV (Spain's roadworthiness inspection, similar to the MOT) also reads the OBD diagnostic system. Repair the fault before you go; clearing the code just before the inspection does not help either, because it counts as a serious defect.[8]
Not sure what is wrong with your car? Describe what you notice in the symptom diagnosis or see all fault codes.
Sources
Every fact on this page links to its source. If you find an error, let us know.
- P2191 – System Too Lean at Higher Load Bank 1 — AutoDTCsAutoDTCs · Technical documentation · published August 2026 · consulted 31 October 2026
- OBD DTC Fehlercode P2191 | System zu mager bei höherer Last - Bank 1CarWiki.de · Technical documentation · consulted 31 October 2026 · in German
- p2191 Generic DTC: System Too Lean at Higher LoadDTCSearch.com (OBD Solutions) · Technical documentation · consulted 31 October 2026
- Code P0171 - System Too Lean: Symptoms, causes, common problems, diagnosticSamarins.com · Technical documentation · published 10 July 2021 · consulted 31 October 2026
- P2193 – System Too Lean at Higher Load Bank 2 — AutoDTCsAutoDTCs · Technical documentation · consulted 31 October 2026
- p2193 Generic DTC: System Too Lean at Higher LoadDTCSearch.com (OBD Solutions) · Technical documentation · consulted 31 October 2026
- On-board diagnosticsWikipedia · Other source · consulted 31 October 2026
- Desmontando mitos: ¿puede pasar mi coche la ITV con el testigo de «avería motor» encendido?Diariomotor · Motoring press · published 8 March 2021 · consulted 2 October 2026 · in Spanish