Powertrain, generic (extended)

P2237 O2 Sensor Positive Current Control Circuit/Open (Bank 1 Sensor 1)

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

P2237 points to an open pump-current line (IP or APE) on the front wide-band sensor of bank 1. With that wire broken the output freezes near its stoichiometric value of roughly 1.5 V and lambda stops moving. Ford sets it on Bosch sensors when 20 s of fuel-control steps and reference-current pulses shift lambda by 0.05 or less; NTK interface chips report the open line directly. VW's 2014 books look for 1.49-1.51 V while the lambda controller deviates by more than 0.10 or fuel has been cut for over 3 s, and Saab's 9-5 2.0 turbo (2010) logs it as Type B. Software updates cure false or damaging cases on VW Jetta/Beetle 2.0 (2013-14, plus a new sensor) and Hyundai Kona 1.6 T-GDI (2024-25). P2238/P2239 are low/high, P2240 is bank 2.

Likely causes

Broken pump-current wire or pushed-back pin between sensor and ECM

Pump cell of the wide-band sensor damaged, for example by catalyst-heating strategy or thermal shock

Engine software that sets the code falsely (update available for some models)

Symptoms

Check engine light
Lambda reading stuck at 1.0 in live data
Higher fuel consumption in open-loop fuelling

Repair estimate

DifficultyMediumDIY possible

Parts and labour€0–400

Time0.3–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

oxygen sensor bank1 sensor1oxygen sensor wiringecm

References: newtonnet.co.uk, static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.