P2252 indicates that the powertrain control module (PCM) has detected a low voltage or current condition in the negative‑side control circuit for the heater of the upstream oxygen (O₂) sensor on bank 1, sensor 1. This circuit regulates the sensor’s heater to bring it to operating temperature quickly; a low‑level signal suggests the heater is not receiving proper power or the PCM cannot drive the circuit correctly.
The internal heater of the sensor may be open or shorted, causing the PCM to see insufficient current flow in the negative control circuit.
Corrosion, damaged insulation, loose pins, or a broken wire in the sensor’s heater circuit can create high resistance or an open circuit, lowering the sensed current.
Many vehicles protect the heater circuit with a fuse; if it opens, the PCM will detect low current on the control side.
The transistor or driver inside the PCM that supplies the negative‑side current can fail, though this is far less common than sensor or wiring problems.
A poor ground connection for the sensor heater can cause the PCM to interpret the circuit as low current even if the heater itself is functional.
No. The PCM is rarely the cause; most P2252 cases stem from a faulty O₂ sensor heater, wiring/connector problems, or a blown fuse. PCM replacement should be considered only after those components have been tested and found good.
You can drive short distances, but the sensor may not reach operating temperature quickly, leading to poorer fuel economy and higher emissions. It is advisable to repair the issue promptly to avoid potential catalytic‑converter damage.
Clearing the code only turns off the light temporarily. If the underlying fault remains, the code will return once the PCM runs its next self‑test.