What it means
The module has detected particulate filter restriction and has commanded limited engine power. The code does not by itself identify the cause of the restriction.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The control module uses pressure and other DPF data to estimate filter restriction. P246C means it has detected restriction severe enough to command limited engine power; the code does not establish whether soot, ash, a sensor fault, or an engine problem caused it.
Common causes
Most likely first.
- DPF heavily loaded with soot after interrupted or failed regenerations
- DPF ash accumulation or physical damage
- Faulty pressure sensor or blocked pressure-sensor hoses
- Engine or fuel-system fault producing excessive soot
Symptoms
- Check engine light or DPF warning light on
- Power loss / limp mode
- Increased fuel consumption
- Failed forced regeneration attempts
How to diagnose it
- Read freeze-frame data and all DPF and engine codes to identify restriction readings, failed regenerations, and faults that could increase soot.
- Check scan-tool DPF pressure and soot-loading data under the conditions specified by the manufacturer to assess whether restriction is plausible.
- Inspect the pressure sensor hoses for soot blockage, cracks, leaks, kinks, or incorrect routing.
- Inspect the DPF pressure sensor connectors and wiring, then test the sensor circuit and readings against the manufacturer's procedure.
- Check for engine or fuel-system faults that can produce excess soot, and inspect the filter for signs of physical damage.
- Determine whether the filter is soot-loaded or ash-filled before attempting a permitted service regeneration or other repair.
Common fixes
- Clear a blocked or repair a leaking or damaged DPF pressure-sensor hose.
- Repair damaged wiring or connector faults at the DPF pressure sensor.
- Correct engine or fuel-system faults that are creating excessive soot.
- Perform a service regeneration if the filter is soot-loaded and the manufacturer's conditions permit it.
- Clean or replace a filter that is ash-loaded or physically damaged, as appropriate.
Can I keep driving?
Because this code indicates limited power, avoid high speeds, steep climbs, towing, and other situations that require strong acceleration; stop safely if power is insufficient for traffic. Continued driving can worsen filter restriction, and a forced regeneration may be unsafe or ineffective until the cause is identified.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.