We do not have a full sheet for this code yet, with its causes and checks. What you see here comes from the OBD2 code standard.
Official name (SAE)
Engine Oil Pressure Sensor/Switch A Circuit
System
Engine and transmission (P)
Group
Vehicle speed, idle and auxiliary inputs
Code type
Generic code: it means the same on every make.
What do I do now?
If the engine light flashes, the car loses a lot of power, overheats or the brakes fail, stop somewhere safe and call for assistance.
If the car drives normally, book a garage and show them this code: its exact meaning and the cause depend on each model.
Tell us what you notice: the diagnosis takes the code, your car and the symptoms into account.
Where is it on the car?
A generic X-ray car with this code's area marked in red: engine. It is a guide, not the layout of your model.
Related faults in the database
Milky oil and low oil-pressure warning in freezing weather (Toyota 2.0 M20A and 2.5 A25A engines)Engine
Engine / equipment
Petrol 2.0 (M20A-FKS), 2.0 hybrid (M20A-FXS) and 2.5 hybrid (A25A-FXS): Corolla, Corolla Cross, C-HR, RAV4 and Camry
Period mentioned
2018–2024
Symptoms
In sub-zero temperatures with many short trips: milky or discoloured oil on the dipstick and under the filler cap, an “Oil Pressure Low” message on the instrument panel and the engine warning light. Codes P05202A (oil pressure sensor stuck) and P052477 (oil pressure too low).
Possible cause described
According to Toyota USA bulletin T-SB-0104-21, moisture from the blow-by gases condenses and builds up in the oil on short trips in extreme cold; when that moisture freezes, oil pressure can drop and the warnings appear. The same milky look appears if coolant mixes with the oil through an internal leak, which is a different and more serious fault.
Check for the garage
With the oil-pressure warning, stop the engine and do not carry on until it is checked. The garage first pressure-tests the cooling system to rule out an internal leak; if there is none, it changes the oil and filter, wipes the milky residue off the cap and checks with the engine warm (coolant at about 50 °C) that the warning and codes do not come back. If they do, the diagnosis must continue with the workshop manual.
Cost cited in the source
An oil and filter change if there is no internal leak; the bulletin does not cover it under warranty.A rough figure from the original database, not an up-to-date quote.