P0172Severity: Medium
P0172 – System Too Rich (Bank 1)
The fuel mixture is too rich (too little air / too much fuel).
What it means
Despite the ECU reducing fuel, the mixture stays rich. Excess fuel, faulty sensors or high fuel pressure can be responsible.
Symptoms
- Black exhaust smoke
- Fuel smell
- Fouled spark plugs
- Increased fuel use
Common causes
- Faulty MAF/MAP sensor
- High fuel pressure/regulator
- Leaking injector
- Dirty air filter
- Faulty O2 sensor
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Frequently asked questions
What does trouble code P0172 mean?
P0172 – System Too Rich (Bank 1). Despite the ECU reducing fuel, the mixture stays rich. Excess fuel, faulty sensors or high fuel pressure can be responsible.
Can I drive with a P0172 code?
You can usually drive short distances, but it's best to have it checked before it gets worse.