What does fault code ECM - 250A long term - fuel trim:upper limit on 2004 volvo S40 mean

You don't say what engine ,does it have E85 flex fuel .assume USA vehicle ?

Fuel Trim
The engine control module (ECM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and emission control. The ECM monitors the heated oxygen sensor (HO2S) signal voltage while in Closed Loop and regulates the fuel delivery by adjusting the pulse width of the fuel injectors based on this signal. The ideal fuel trim values are around 0 percent for both short term and long term fuel trim. A positive fuel trim value indicates the ECM is adding fuel in order to compensate for a lean condition by increasing the pulse width. A negative fuel trim value indicates that the ECM is reducing the amount of fuel in order to compensate for a rich condition by decreasing the pulse width. A change made to the fuel delivery changes the short term and long term fuel trim values. The short term fuel trim values change rapidly in response to the HO2S signal voltage. These changes fine tune the engine fueling. The long term fuel trim makes coarse adjustments to the fueling in order to re-center and restore control to short term fuel trim. A scan tool can be used to monitor the short term and long term fuel trim values. The long term fuel trim diagnostic is based on an average of several of the long term speed load learn cells. The ECM selects the cells based on the engine speed and engine load. If the ECM detects an excessive lean or rich condition, the ECM will set a fuel trim diagnostic trouble code (DTC).

You need to have someone scan the OBD system and tell you if the fuel trim is at the upper or lower limit. Then you will need to fault trace from the following list Possible source

• Upper limit:
  intake air leakage
  exhaust system air leakage
  defective heated oxygen sensor (HO2S)

Lower limit:

• intake air leakage
  high fuel pressure
  leaking injectors
  defective mass air flow (MAF) sensor
  contaminated engine oil
  oil level too high
  defective heated oxygen sensor (HO2S)

Error description:
ECM-250A Long-term trim - Upper Limit

code p1124 refers to long term fuel trim--additive-mixture too lean===causes --HO2s---fuel pressure--fuel system---mechanical fault---ECM

Check, test or replace MAF sensor.

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code efi-232 is long term fuel trim, idling. intake/exhaust leak, fuel pressure, excessive fuel in engine oil, engine oil level to high. injectors. EVAP canister purge valve, wiring MAF sensor, ECT sensor HO2S. hope this helps and let me know if you need any more info

The control module receives information from the heated oxygen sensor (HO2S) about the fuel/air mixture when idling at both the lower and upper part-load range - If the fuel/air mixture deviates from [lambda]=1 the short-term fuel trim will compensate for this by adjusting injection time so that [lambda]=1 is achieved. When the short-term fuel trim makes an adjustment, the integrator median must be adjusted by the long-term trim. Diagnostic trouble code (DTC) ECM-261A will be stored when the long-term trim must be adjusted to maximum in the lower part of the load area.

p0172 is not a volvo code so may not be correct but converted to volvo is code 250a long term fuel upper limit (lean vac leak) ck all vac hoses and replace the canister purge valve mounted on the radiator (about $40.00 part) then reset all codes

Faults can happen from day one, on. That is why there is a warning system.
If the warning light is on, you must access the computer system to access which fault code is present. Many different companies manufacture tools to do this from an inexpensive generic one from Launch Tech of China to the original factory unit made for Volvo by Balco. Depending on the fault code, the most common one that I see is caused by the fuel cap either installed incorrectly or not fully tightenned. Check your fuel cap and if it is not installed correctly or not fully tightenned, please re-install. If the fuel cap was the problem, the warning light will go off by itself in a few days.