P2237: O2 Sensor Positive Current Control Circuit Open (Bank 1, Sensor 1)
Key takeaways
- P2237 means the engine computer found an open circuit on the positive current (pump) wire of the upstream air-fuel sensor on bank 1.
- The car is usually safe to drive; expect a little worse fuel economy and a failed emissions test until it's fixed.
- Check the sensor connector and wiring first: several manufacturer bulletins for this code fix connectors or software, not only the sensor.
- A wiring repair runs $100–$250 and a new upstream air-fuel sensor $150–$400 at a US independent shop.
What P2237 means
One of the wires to your front oxygen sensor looks broken to the engine computer. Scanners call it O2 Sensor Positive Current Control Circuit/Open (Bank 1, Sensor 1).
This code belongs to the wide-range oxygen sensor, often called an air-fuel ratio sensor, that many engines use before the catalytic converter. Unlike an older on-off O2 sensor, it has a small “pump” cell. The engine computer drives a current through that cell and reads how much it takes to balance the exhaust, which tells it the exact air-fuel mixture. P2237 means the computer sees the positive side of that pump-current circuit as open: no current is flowing where it should.
Sensor 1 is the upstream sensor, before the converter. Bank 1 is the side of the engine with cylinder 1; on a four-cylinder there’s only one bank.
Is it safe to drive?
Yes, in most cases. Without a reading from the sensor, the engine computer runs on a preset fuel mixture. The engine keeps running, but fuel economy dips, emissions rise, and you’ll fail an emissions or plug-in inspection with the light on.
What changes the answer: if the check engine light starts flashing, the engine runs rough or hesitates, or you smell raw fuel, you have more than a sensor circuit fault. Keep trips short and get it checked. A long stretch on a rich mixture can overheat the catalytic converter.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Loose, corroded or wet sensor connector | Water, green corrosion or a pushed-back pin in the plug; code comes and goes | $100–$250 |
| Damaged wiring between the sensor and the engine computer | Wires melted on the exhaust, chafed or chewed; circuit tests open end to end | $100–$250 |
| Failed air-fuel sensor (internal open) | Wiring tests good to the plug, sensor’s pump cell reads open or far out of spec | $150–$400 |
| Engine computer software (some makes) | A bulletin for your model and year names P2237 | $100–$200, often $0 under warranty or a bulletin |
| Engine computer driver fault | Everything above checks out and the computer still shows no current | Rare; get a second diagnosis first |
What to check first
- Read all the codes. If other circuit codes for the same sensor appear, such as P2251 or P2626, suspect the connector or harness first, since they share it.
- Look at the connector and wiring. Follow the sensor wire from the exhaust to the plug. Look for melted insulation, rodent damage, and moisture or corrosion inside the connector.
- Check continuity. With the sensor unplugged, a shop checks each wire from the plug back to the engine computer, then the sensor’s own pins.
- Check for bulletins. The pattern is connectors and software. Dodge’s bulletin for 2010–2012 Ram 2500 replaces the O2 sensor connectors and says not to replace parts first. Volkswagen’s bulletin for 2013–2014 Beetle updates programming along with a sensor replacement, and Ram and Jeep bulletins for 2015 3.0L engines reprogram the engine computer. Smart and Land Rover also have bulletins naming this code.
- Clear it and drive, after a repair. If you fixed a connector, clear the code and drive a few cold starts to confirm it stays off.
Our O2 sensor check engine light guide covers the other sensor codes and how to tell a bad sensor from a problem it’s reporting.
NHTSA’s complaint files hold no owner complaints that mention P2237. It’s an uncommon code, or owners don’t quote it when they file.
What it costs
The cheap outcome is a connector cleaned and resealed or a software update, about $100–$250. The common outcome is a new upstream air-fuel sensor at $150–$400, parts and labor; wide-range sensors sit at the top of that range, and seized sensors add labor. Testing the wiring before buying a sensor costs little and catches the connector problems the bulletins describe. If you’re unsure which way your readings point, ask our AI mechanic with your code list and car.
Related codes
P2237 often sets with P2251 (the negative current circuit), P2626 (the pumping current trim circuit) or P2243 (the reference voltage circuit) on the same sensor. If it comes with P0135, the sensor’s heater circuit has a fault too, which also points at the shared connector.
What owners report to NHTSA
No consumer complaints filed with NHTSA mention P2237. That usually means it's rare, or owners don't quote the code when they file.
Manufacturer service bulletins that name P2237
16 technical service bulletins and manufacturer communications filed with NHTSA mention P2237, from 6 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- SMART FORTWO (2005, 2008, 2009, 2011), bulletin 10136113: Engine diagnosis warning lamp (CEL) is active due to fault codes - P2237 & P2626.
- LAND ROVER RANGE ROVER (2016), bulletin 10105881: "ISSUE: THE CUSTOMER MAY OBSERVE A MIL IN THE INSTRUMENT CLUSTER RELATING TO THE ENGINE SYSTEM (CHECK ENGINE LIGHT) AND ONE OR MORE CODES STORED IN THE PCM RELATING TO HEATED OXYGEN SENSOR (HO2S) IN THE EXHAUST SYSTEM. T…
- RAM 1500 (2015), bulletin 10148989: Flash: 3.0L Powertrain Diagnostic And System Enhancements This bulletin involves reprogramming the Powertrain Control Module (PCM) with the latest available software. A small number of customers may experience a Malfunct…
- JEEP GRAND CHEROKEE (2015), bulletin 10159959: Flash: 3.0L Powertrain Diagnostic And System Enhancements This bulletin involves reprogramming Powertrain Control Module (PCM) with latest available software. It also involves cleaning or replacement of Exhaust Gas Tempe…
- VOLKSWAGEN BEETLE (2013, 2014), bulletin 10121248: Technical Bulletin: Update Programming to Eliminate O2 Sensor DTC P2414 and/or P2237 along with O2 Sensor Replacement
- DODGE RAM 2500 (2010, 2011, 2012), bulletin 10128943: Malfunction Indicator Lamp Illumination Due To Oxygen Sensor This bulletin involves replacement of the Oxygen Sensor Connectors for any Oxygen Sensor related DTC. Do NOT replace any parts prior to performing this bulleti…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
Does P2237 mean the O2 sensor is bad?
Not always. The code says one circuit reads open, which can be a broken wire, a loose or corroded connector pin, or a failed sensor. Check the connector and wiring first; replace the sensor when the circuit tests good to the sensor and the sensor itself reads open.
Can I drive with P2237?
Usually yes. The engine falls back to a preset fuel mixture, so it runs, but fuel economy drops and emissions rise. Get it checked sooner if the check engine light flashes, the engine runs rough or you smell fuel.
Which sensor is bank 1 sensor 1?
Sensor 1 is the upstream sensor, before the catalytic converter. Bank 1 is the side of the engine with cylinder 1; on a four-cylinder there's only one bank, so it's simply the front sensor.
Why does P2237 come with P2251 or P2626?
They are other wires of the same air-fuel sensor. Several at once usually points to the connector or harness shared by all of them, or to a sensor that failed internally, rather than to separate problems.