DPF Restriction - Forced Limited Power
The P246C code indicates that the Diesel Particulate Filter (DPF) has become excessively restricted, causing the engine control module (ECM) to limit engine power to prevent damage. This restriction is typically due to excessive soot accumulation that cannot be burned off during normal regeneration cycles, often caused by frequent short trips, low exhaust temperatures, or a faulty regeneration system.
1. Most Common Causes
- Excessive soot buildup from frequent short trips
- Faulty DPF pressure sensor
- Failed or clogged diesel oxidation catalyst (DOC)
- Malfunctioning exhaust gas temperature sensor
- Incorrect engine oil type (high ash content)
2. Symptoms You Will Notice
- Reduced engine power and acceleration
- Illuminated check engine light
- Increased fuel consumption
- Possible regeneration failure or frequent regeneration attempts
3. Step-by-Step Diagnosis
Step 1: Scan for codes and check freeze frame data to confirm P246C.
Step 2: Inspect DPF pressure sensor readings and compare to specifications.
Step 3: Perform a forced regeneration using a scan tool to attempt to clear the DPF.
Step 4: If regeneration fails, remove and inspect the DPF for physical damage or excessive ash.
Step 5: Check exhaust gas temperature sensors and DOC for proper operation.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Driving with reduced power is possible but not recommended for long distances as it may cause further damage or leave you stranded. Immediate diagnosis is advised.
How much does it cost to fix?▼
Costs vary: forced regeneration may be $100-$200, DPF cleaning $300-$600, and DPF replacement $800-$2,000 or more.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.