System: Powertrain (P-Code)
SAE Standard (Generic)
Family: Fuel Trim Rich
Code P0172: System Too Rich Bank 1
Diagnostic & Technical Explanation
Code P0172 (System Too Rich Bank 1) sets when the ECM must remove more fuel than the calibrated limit allows to correct a rich condition on the indicated bank. Leading causes are a leaking fuel injector, a stuck-open fuel pressure regulator, a fouled MAF sensor overreporting airflow, or a failing fuel pressure sensor.
First-listed procedure
Rank #1
Clean MAF sensor and inspect for false-high airflow readings
Easy DIY
This is the first procedure in the authored
consideration order, not a measured cause likelihood. Execute it only when its prerequisites
and diagnostic findings support it. Its cost and labor estimates (where known), the step-by-step procedure and the
remaining 2 procedure(s) are in the licensed dataset. Ordering context.
Full family: Fuel Trim Rich
What this page does not show
This page publishes the fault mechanism and the code index. The licensed dataset adds, for
every one of the 15,886 codes, the full authored repair set (56,729 procedures in total)
with the fields deliberately withheld here:
- Procedures 2..n after the first-listed procedure
- Aftermarket parts cost ranges in USD (
est_parts_cost_min/max_usd)
- Professional labor-hour estimates (
est_labor_hours)
- Step-by-step diagnostic and repair instructions
- Replacement-part mappings and catalog lookups
- 6,637 manufacturer-specific OEM codes across 32 makes ($149 tier)