P253F: Engine Oil Deteriorated

What it means

The engine oil is reported as deteriorated. The code does not establish the oil condition measurement method or required service response.

At a glance

• Usually lights the check-engine light

How it works

P253F indicates that the engine oil condition has been reported as deteriorated; the monitoring method depends on the vehicle. The control module sets the code when its oil-condition assessment reaches a deterioration threshold, which can happen after an overdue service interval or when repeated diesel particulate filter (DPF) regenerations contribute to fuel dilution.

Common causes

Most likely first.

1. Service interval exceeded
2. High DPF regeneration load with fuel dilution

Symptoms

• Check-engine or oil-service warning light
• Oil-change or service reminder may appear
• Engine may run less smoothly if oil condition is severely degraded

How to diagnose it

1. Read freeze-frame data and any oil-life or service information to establish when the code was recorded and whether service is overdue.
2. Check the oil level and condition using the vehicle's specified method, and look for an unexpectedly rising level that could indicate fuel dilution.
3. Review service history and, on a diesel, check for frequent or incomplete DPF regeneration events that may have diluted the oil.
4. Check for related engine or DPF faults that could explain repeated regeneration or rough running.
5. After correcting the cause and servicing the oil as specified, reset the oil-life monitor or code only through the vehicle's prescribed procedure.

Common fixes

• Change the engine oil and filter if the service interval has been exceeded or oil condition warrants it.
• Correct a DPF regeneration problem that is contributing to fuel dilution.
• Repair related engine faults that are causing repeated or incomplete regenerations.
• Reset the oil-life monitor using the vehicle's specified procedure after service.

Can I keep driving?

Arrange an oil and service check soon, and avoid heavy loads if the oil level is rising or the engine runs poorly. Severely degraded or fuel-diluted oil can reduce lubrication and increase engine wear.