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, often from short trips or incomplete regeneration cycles. The forced limited power mode reduces throttle response and overall performance to protect the DPF and engine.
01. Most Common Causes
- Excessive soot buildup in DPF due to frequent short trips
- Faulty DPF pressure sensor or wiring
- Failed DPF regeneration cycles (e.g., due to low exhaust temperature)
- Clogged or malfunctioning exhaust gas recirculation (EGR) system
02. Symptoms You Will Notice
- Reduced engine power and acceleration
- Illuminated check engine light (MIL)
- Increased fuel consumption
- Possible DPF warning light on dashboard
03. Step-by-Step Diagnosis
Step 1: Scan for codes and check freeze frame data to confirm P246C.
Step 2: Inspect DPF pressure sensor and wiring for damage or corrosion.
Step 3: Perform a forced DPF regeneration using a scan tool to clear soot.
Step 4: Check for exhaust leaks or restrictions upstream of the DPF.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the forced limited power mode can reduce performance and may lead to further DPF damage. Short trips to a repair shop are acceptable.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. If a forced regeneration is needed, it may be included. Replacement of the DPF pressure sensor or cleaning the DPF can add $200-$600.