Lambda sensorsGeneric OBD-II codeUrgency: Garage soon
Code P2237: front lambda sensor: current circuit open
What code P2237 means
The ECU has detected inconsistent signals from the bank 1, sensor 1 oxygen sensor (the front one, upstream of the catalytic converter): the positive current control circuit is open or there is no signal.[1][2]
This type of code affects wideband sensors, and its exact definition may vary depending on the manufacturer.[1]
Original definition (SAE J2012): O2 Sensor Positive Current Control Circuit/Open Bank 1 Sensor 1[1]
Causes of P2237
From most to least likely, according to the sources.
Symptoms
- Engine warning light on.[1][2]Engine warning light: faults that cause it
- Higher fuel consumption.[1][2]Uses more fuel: faults that cause it
- Reduced or uneven engine performance.[1][2]Less power: faults that cause it
- Jerking when accelerating and uneven idle.[2]Jerking: faults that cause it
How to diagnose P2237
In order: from the most likely and cheapest to check to the most expensive.
- 1Confirm the code with a diagnostic tool and check for other codes from the same sensor, its heater or the mixture.[1]
- 2Inspect the wiring and connector of the bank 1 front sensor: broken or melted wires, or corroded terminals.[1][2]
- 3Check that there are no exhaust leaks near the sensor.[1][2]
- 4Check the sensor circuit's fuses and relays before replacing anything.[2]
- 5If the wiring and supply are fine, replace the sensor; the ECU should only be suspected at the end.[1][2]
Can I keep driving with P2237?
Garage soon
The sources do not specify the severity. With the front sensor giving no reliable signal, the ECU loses precise control of the mixture, which means higher consumption and poorer running, so get it checked without delay.[1][2]
Documented faults related to P2237
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.
Frequently asked questions
What does P2237 mean?
That the ECU has detected an open circuit in the current control of the bank 1 front oxygen sensor, normally a wideband sensor.[1]
Does the lambda sensor have to be replaced?
Often yes, it is one of the main causes, but first rule out a damaged wire, a corroded connector or an exhaust leak.[1][2]
Can I drive with code P2237?
The sources set no limit. The car usually keeps running, but with higher consumption and poorer performance; get it diagnosed soon.[1][2]
How much can the repair cost?
CarWiki gives about €80-250 for replacing the sensor and €50-200 for repairing the wiring, as reference estimates in Germany. The cost varies a lot depending on the car.[2]
Will I pass the MOT with code P2237?
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.
- P2237: O2 Sensor Positive Current Control Circuit/Open Bank 1 Sensor 1CarParts.com · Technical documentation · consulted 29 October 2026
- OBD DTC Fehlercode P2237CarWiki · Technical documentation · consulted 29 October 2026 · in German
- 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