OBD-II Code · Sensors
P2237
O2 Sensor Pumping Current Circuit Open (B1S1)
Severity
medium
Worth booking. It costs fuel, emissions or comfort until it is fixed.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$200–$500
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
Wideband O2 pump circuit open.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Likely causes
- Failed wideband sensorMost common
- Wiring
Read the full diagnostic procedureP2237 sets on a wideband (AFR / air-fuel-ratio) upstream O2 sensor on bank 1 when the ECU detects an open or implausibly low pumping-current control…
P2237 sets on a wideband (AFR / air-fuel-ratio) upstream O2 sensor on bank 1 when the ECU detects an open or implausibly low pumping-current control circuit — the wideband sensor needs the ECU to actively drive a small pumping current (typically ±2 mA across the lambda 1.0 stoichiometric point) through the sensor's pumping cell to maintain a fixed oxygen concentration at the Nernst reference, and the actual lambda is read off how much current it takes. When the pumping-current driver circuit is open or the wiring to it is broken, the ECU can't control the sensor and sets P2237.
Cheapest-first ladder
- inspect the connector at the sensor for corrosion and pushed pins — the wideband connector typically has 5-6 wires (heater B+, heater ground, pump cell, Nernst cell, virtual-ground reference, sometimes calibration resistor) and a single corroded pin kills the pumping circuit.
- Backprobe the pump-cell wire with the engine warm and look for the ~3V virtual-ground sitting steady; if it's pinned to 0V or 5V, the circuit is open or shorted.
- DMM the heater pins (2-4 ohms cold on most wideband sensors) — a sensor with a failed heater never reaches the 700°C+ element temp it needs to pump current.
- Wideband sensors are far more expensive than narrow-bands ($150-$350 OEM) so verify the harness side before parts-cannoning.
Vehicle-specific patterns2005-2012 Toyota 2GR-FE 3.5L V6 (Camry, Avalon, Sienna, Highlander) throws P2237 routinely past 120k miles — Denso wideband sensors degrade and the p…
- 2005-2012Toyota 2GR-FE 3.5L V6 (Camry, Avalon, Sienna, Highlander) throws P2237 routinely past 120k miles — Denso wideband sensors degrade and the pumping circuit eventually opens internally; replace with OEM Denso, aftermarket Bosch widebands often throw new codes on this platform.
- 2006-2014Subaru EJ25 (Forester, Outback, Legacy) throws P2237 from a chafed front O2 harness where it routes past the exhaust crossover, plus genuine sensor failure around 100k miles; the front sensor is the wideband and the rear narrow-band lasts much longer.
- 2008-2013BMW N55 turbo I6 (335i, 535i, X3, X5) throws P2237 from a connector heat-damage issue near the turbo and from wideband element failure around 80k-110k miles.
- 2007-2014Mazda 2.3L DISI turbo (Mazdaspeed 3/6, CX-7) throws P2237 from oil-fouled wideband elements when the turbo seals leak past the compressor.
Estimated repair$200 to $550.
Look up another code
P2237 — frequently asked
What does a P2237 code mean?
Wideband O2 pump circuit open.
What causes a P2237 code?
Common causes: Failed wideband sensor; Wiring.
What are the symptoms of a P2237 code?
Typical symptoms: Check engine light.
Is it safe to drive with a P2237 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $200-$500.
How do I diagnose a P2237 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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