Reductant System Performance Bank 1
The P204F code indicates that the powertrain control module (PCM) has detected a performance issue with the reductant (DEF) injection system on Bank 1. This typically means the system is not delivering the correct amount of diesel exhaust fluid to the selective catalytic reduction (SCR) catalyst, which can lead to increased NOx emissions. Common causes include a faulty reductant injector, clogged or leaking lines, a defective pump, or issues with the DEF quality or level.
01. Most Common Causes
- Faulty reductant injector
- Clogged or leaking DEF lines
- Defective DEF pump
- Poor quality or contaminated DEF fluid
- Faulty NOx sensor or SCR catalyst
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine performance or power
- Increased fuel consumption
- Excessive exhaust smoke (white or black)
- Failed emissions test
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check freeze frame data.
Step 2: Inspect DEF fluid level and quality; replace if contaminated.
Step 3: Visually inspect DEF injector, lines, and pump for leaks or damage.
Step 4: Test DEF pump pressure and injector operation using a scan tool.
Step 5: Check NOx sensor readings and compare to expected values.
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 it can cause damage to the SCR system and lead to costly repairs. The vehicle may also enter limp mode to protect the engine.
How much does it cost to fix?▼
Repair costs vary widely depending on the root cause, typically ranging from $150 to $600 for parts and labor. Injector replacement can be on the higher end.