p2238 oxygen sensor current circuit low ?

2007 TOYOTA COROLLA
270,000 MILES • 1.8L • AUTOMATIC
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YAZIDAN
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p2238 oxygen sensor pumping current circuit low (for a/f sensor) (bank 1 sensor 1). what is the common cause of the code and other causes ? is the code related to the heater circuit or to the sensor sense circuit ?also what i noticed is that the o2 sensor heater monitor says n/a usually when the monitor is not complete it says inc and when ready it says ok .

thank you
Aug 19, 2026 at 6:13 PM
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STRAILER
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Hello,

The code P2238 refers primarily to the sensing/pumping-current portion of the upstream air/fuel-ratio sensor (Bank 1 Sensor 1), rather than being specifically a heater-circuit code. This can be caused by a cylinder misfire, can I ask how the engine is running? If the engine is running okay I would replace the primary oxygen sensor. Here is the location. Please clear the codes once the repair is completed.
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Aug 20, 2026 at 5:40 PM
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YAZIDAN
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the engine runs good no misfire or hesitation. I found a crack in the exhaust manifold. i guess corollas are famous for cracked exhaust manifold .the old AFR is a Toyota one .i bought a Denso
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Aug 22, 2026 at 3:26 AM
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STRAILER
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Yep, you found the problem, nice work, I would have it rewelded or try to find a used one on Ebay.
Aug 22, 2026 at 8:43 AM
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