P0172 System too rich, bank 1
- System
- Powertrain - engine and transmission
What P0172 means
"System too rich, bank 1" is P0171 read the other way: the fuel correction the computer had to apply on bank 1 reached the end of its range in the direction that takes fuel away. It describes where the correction sat, not what moved it there. Bank 1 is the cylinder group the engine computer numbers first, and P0175 is the same reading on bank 2.
This is a standard code. It means the same thing on every make of vehicle.
What the program shows for P0172
The same two readings carry it: Short fuel trim and Long fuel trim on the Dashboard, with Air/fuel ratio, Commanded lambda and O2 sensor (rear) beside them. The Analysis screen's At idle figures give the total correction over a recording, and comparing two recordings shows the change in short, long and total trim at idle.
The Dashboard shows Short fuel trim and Long fuel trim, Air flow, Manifold pressure, Intake air temp, Coolant temp, Throttle position, Accelerator pedal, Air/fuel ratio, O2 sensor (rear), O2 sensor current and whether the Fuel system is in closed loop. Record a drive and the Analysis screen gives the total correction At idle, Fuel trim against air flow, and whether the air flow and pressure sensors agree; the Full scan's On-board self-tests list the Oxygen sensor results by bank and sensor. Record before and after a repair and Compare shows the change in short, long and total trim at idle plus which codes are Gone, New or Still there.
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