Code
P0172
Fuel / Air
System too rich — Bank 1
The engine runs with too much fuel or too little air on bank 1.
Advertisement
Most likely causes
- Faulty mass airflow sensor
- Clogged air filter
- Faulty oxygen sensor
- Leaking fuel pressure regulator
- Leaking injector
Symptoms you may notice
- Check engine light
- Fuel smell
- Poor fuel economy
- Black exhaust smoke
Checks to run
- Check MAF readings against spec
- Test fuel pressure
- Inspect injectors for leaks
- Look for stored rich-running causes
Tools you may need
OBD-II scanner
Fuel pressure gauge
Multimeter
Always diagnose before replacing. Codes share symptoms; confirm the cause with measurements before buying parts.