Error code

OBD2 P0172

OBD2P0172
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

System Too Rich.

Severity

moderateCan drive, but expect poor performance and potential damage to the catalytic converter.

Summary

P0172 indicates that the fuel system is too rich in bank 1 of the engine.

Symptoms

  • Poor fuel economy
  • Rough idling or lack of power on acceleration
  • Black exhaust smoke and strong fuel odor

Common Causes

  • Contaminated MAF sensor, especially with aftermarket filters
  • Leaking fuel injector
  • Faulty fuel pressure regulator
  • Dirt or grime contamination in the air intake system

Diagnosis

  1. Check fuel pressure and ensure it is within proper range
  2. Verify ECT (engine coolant temperature) and IAT (intake air temperature) readings are normal
  3. Inspect for leaking fuel injectors or fuel pressure regulator issues

Fixes

  • Replace contaminated MAF sensor and install a new air filter
  • Repair or replace faulty fuel injector(s)

FAQ

What does P0172 mean?

P0172 indicates that the engine is running too rich, meaning there's an excess of fuel in the combustion process.

How do I fix a contaminated MAF sensor?

Replace the contaminated MAF sensor and install a new air filter to ensure proper airflow.

View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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