Lambda sensorsGeneric OBD-II codeUrgency: Garage soon
Code P2195: front lambda sensor stuck lean (B1S1)
What code P2195 means
The front oxygen sensor on bank 1 (the one before the catalytic converter) continuously indicates a lean mixture, without reacting to changes. Either the mixture really is lean or the sensor is faulty.[1][2]
In the documented example of a Toyota car with a wideband sensor, the code is set when the voltage stays above 3.8 V for at least 5 seconds and the rear sensor confirms that the exhaust is lean; the signal may vary from one brand to another.[2]
Original definition (SAE J2012): O2 Sensor Signal Stuck Lean (Bank 1 Sensor 1)[1][2]
Causes of P2195
From most to least likely, according to the sources.
- 1A genuinely lean mixture: vacuum or air leaks in the intake, low fuel pressure or a clogged injector.[1][2]
- 2Front sensor faulty or with a degraded element.[1][2]
- 3Faulty sensor heater or its relay: a cold sensor gives invalid readings.[2]
- 4Open signal wire, corroded connectors or a wiring fault.[1][2]
- 5Exhaust leak or faulty injectors and a failed fuel pressure regulator.[1]
Symptoms
- Engine warning light on (it may need two drive cycles).[1][2]Engine warning light: faults that cause it
- Uneven idle, hesitation or jerking at low load.[1][2]Jerking: faults that cause it
- Increased fuel consumption.[1][2]Uses more fuel: faults that cause it
- Possible slight loss of power.[1][2]Less power: faults that cause it
How to diagnose P2195
In order: from the most likely and cheapest to check to the most expensive.
- 1Use a diagnostic tool to read the sensor voltage and the short- and long-term fuel trims for bank 1. Strongly positive trims (more than +10%) point to a genuinely lean mixture and not just a faulty sensor.[2]
- 2Look for air or vacuum leaks in the intake: hoses, manifold gaskets and pipes.[2]
- 3Check the sensor heater and whether the tool shows the sensor as active after a warm start.[2]
- 4Check the fuel pressure and the condition of the bank 1 injectors.[2]
- 5Inspect the sensor wiring and connector and, only if everything above is fine, replace the front sensor.[1][2]
Can I keep driving with P2195?
Garage soon
AutoDTCs recommends diagnosing it within a week or two, because a lean mixture under high load can cause misfires and overheat the catalytic converter, and a faulty sensor leaves the closed-loop mixture uncontrolled. CarWiki does not go into severity.[2]
Documented faults related to P2195
Known faults of specific engines and cars, with their repair cost, the affected years and their sources.
Engine sensors: 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».
- Medium severityFrequency: Common2.0 TDIClogged particulate filter or faulty pressure sensorThe 2.0 TDI's particulate filter clogs if the car mostly makes short journeys, because it never gets to regenerate; sometimes the fault is just the differential pressure sensor. Cleaning it costs around €200 and replacing it, €800 to €3,000.Repair (garage): €800–€3,000
- Medium severityFrequency: Common1.4 and 1.6 8vCrankshaft position sensor failure (TDC sensor)The crankshaft position sensor (capteur PMH, or TDC sensor) appears repeatedly in the reliability sources for the Clio II, the Kangoo I and the Dacia Logan I with this engine, with hard cold starting or stalling as the main symptoms. It is a cheap part, but the failure can leave you stranded.
- Medium severityFrequency: Common1.4 and 1.6 16vCrankshaft position sensor failureThe crankshaft position sensor (capteur PMH) appears repeatedly in the reliability sources for almost every generation with this engine, with hard cold starting, stalling or the car cutting out unexpectedly. It is a cheap part, but the failure can leave you stranded.
Wiring, connectors and short circuits: the most serious faults by engine and car
- Critical severityFrequency: OccasionalBMW N62 / N63Additional turbo coolant pump with a risk of short circuit and fireIn 2011 BMW recalled 5, 6 and 7 Series, X5 and X6 models built between 2007 and 2011 because of the additional turbo coolant pump: moisture, a short circuit and, in extreme cases, a fire. In 2012 there was another campaign for a crack in the pump, with a more robust version.
- High severityFrequency: Occasional1.3 TCeBlown fuel pump fuseOn the Renault Captur II and Clio V with the 1.3 TCe engine, a 20-amp fuse can blow and leave the car without an engine. According to L'argus, in April 2021 this fault still had no factory fix; the official service centre's diagnosis includes checking, and sometimes replacing, the catalytic converter.
- High severityFrequency: OccasionalM264/M254Poorly tightened 48 V earth wiring in the mild-hybrid system (fire risk)Mercedes-Benz has issued several recalls (2022-2025) because the 12 V and 48 V earth connections of some cars with a 48 V system may be poorly tightened: resistance rises, the connection heats up and a fire cannot be ruled out. The official workshop checks them and repairs them if necessary in an hour or more.
- High severityFrequency: Occasional1.9 TDIUnit injector tappet wear and injector wiring damageOn the unit injector system, the tappets that operate the injectors can wear if the oil is not changed on time, and the injector wiring can be damaged by contact with oil, causing misfires or loss of power.
- Critical severityFrequency: CommonRover 75Seat SRS connector fault with airbag and seatbelt warning light onAuto Express warns that the Rover 75's seat SRS connector can cause the airbags to fail, and dealers were fixing it with revised connectors. The Dutch APK inspection puts the airbag or seatbelt fault warning among the most frequent defects across almost all series.
- Critical severityFrequency: OccasionalAlfa Romeo GiuliettaShort circuit from badly routed wiring that can prevent gear shifting (KBA campaign, 2010-2015)Yes: according to Germany's KBA, on Alfa Romeo Giulietta cars built between 2010 and 2015 inadequate cable routing could cause a short circuit and, as a result, gear-shift failure.
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
Frequently asked questions
What does "stuck lean" mean?
That the sensor signal stays continuously in the lean mixture range and does not reflect changes in the mixture. It can be because the mixture really is lean or because the sensor is faulty.[1][2]
Can I keep driving with P2195?
You can get to the garage, but it should be diagnosed within a few weeks: under high load a lean mixture can cause misfires and heat the catalytic converter.[2]
Does the lambda sensor need replacing?
Only if air leaks, fuel pressure and wiring have been ruled out first, because a genuinely lean mixture gives the same code with a healthy sensor.[1][2]
What is the difference from P2196?
P2196 is the same problem but with the signal stuck rich; P2195 is the lean version. Both refer to the front sensor on bank 1.[1]
Will I pass the MOT with code P2195?
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.[3]
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.
- OBD DTC Fehlercode P2195CarWiki · Technical documentation · consulted 29 October 2026 · in German
- P2195 - O2 Sensor Signal Stuck Lean Bank 1 Sensor 1AutoDTCs · Technical documentation · consulted 29 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