P0172 Moderate Powertrain

System Too Rich (Bank 1)

Common Causes

Leaking or stuck-open fuel injector
Faulty fuel pressure regulator stuck closed
Failed upstream O2 sensor
Restricted air filter
Coolant leak into combustion chamber

Common Symptoms

Rough Idle Engine Stalling Engine Hesitation on Acceleration Engine Misfires Engine Surging at Idle Black Exhaust Smoke Poor Fuel Economy

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Quick Info

Code P0172
System Powertrain
Severity Moderate

Disclaimer

This information is for diagnostic guidance only. Always verify repairs with a qualified technician before performing safety-critical work.

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