P2238: O2 Sensor Positive Current Control Circuit Low Bank 1 Sensor 1
What to do
Expect worse economy and reduced power while the module fuels without a mixture measurement. Ask for the harness to be inspected where it approaches the exhaust — heat damage there is the usual cause, and it is a wiring repair rather than a sensor.
What this code means
The positive current control circuit reads below its valid range, normally a short to ground. The module shuts the affected output down rather than continue feeding a short, so the pump cell stops and the mixture measurement is lost — the mechanism is at P2237.
Because this line carries a small driven current rather than a switched load, external damage is a more likely cause than internal failure. The harness runs from the module to a sensor mounted on the exhaust, which is the hottest part of its route and where insulation degrades first.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Melted wiring against the exhaust · moderate
- Faulty oxygen sensor · moderate
Less common
- Corroded or loose connector · easy
- Damaged wiring harness · moderate
Symptoms
Components involved
Information, not instruction
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Community experience
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