Reductant Pressure Too Low
The P20E8 code indicates that the diesel exhaust fluid (DEF) system has detected insufficient pressure in the reductant delivery system. This typically occurs when the DEF pump cannot maintain the required pressure to inject DEF into the exhaust stream, often due to a faulty pump, clogged lines, or a defective pressure sensor. The system may also detect low pressure if the DEF level is low or if there is a leak in the system.
01. Most Common Causes
- Low DEF level
- Faulty DEF pump
- Clogged or leaking DEF lines
- Defective reductant pressure sensor
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Possible diesel exhaust fluid warning on dashboard
03. Step-by-Step Diagnosis
Step 1: Check DEF level and top off if low.
Step 2: Inspect DEF lines for leaks, kinks, or blockages.
Step 3: Test DEF pump operation and pressure using a scan tool.
Step 4: Replace faulty components (pump, sensor, or lines) as needed.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Driving with P20E8 may cause reduced power and eventual inability to start if DEF system is disabled. It is not recommended for long distances.
How much does it cost to fix?▼
Costs vary from $50 for a simple DEF refill to $150 for sensor replacement, but pump replacement can be more expensive.