P2A38O2 Sensor Positive Current Control Circuit/Open Bank 1 Sensor 3
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2A38 reports that the lead carrying positive current control for bank 1's third oxygen sensor has no continuity. That sensor sits behind a second converter or a later aftertreatment stage, and the code only makes sense where this position carries a wide-band probe: through this lead (pin APE/IP on a Bosch LSU 4.9) the controller drives between about −2 and +2.25 mA into the pump cell. No manufacturer documents P2A38 publicly. For the upstream twin P2237, Ford's 2012 summary spots a broken IP wire because lambda barely moves during deliberate reference-current pulses; its own third sensors are switching types with heater codes only. P2A39/P2A3A are the low/high faults, P2A3B the open return. The lamp lights, while driving feels unchanged.
- What you may notice
- Check engine light
- Sensor 3 value frozen near lambda 1 in live data
- Downstream emission monitors not completed
- Likely causes
- LikelyBroken pump-current wire or pushed-back pin in the sensor plug
- PossibleSensor plug loose or not latched after exhaust work
- RareInternal break in the pump cell of the probe
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €0 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.