Milky oil and low oil-pressure warning in freezing weather (Toyota 2.0 M20A and 2.5 A25A engines)

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.

Sources from the original database