P1171 = ECM-261A= Long-term fuel trim Upper limit
P1181 =ECM-271ALong-term fuel trim, bank 2 Upper limit
Diagnostic trouble code (DTC) information
Condition
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 λ=1, the short-term fuel trim will compensate for this by adjusting the injection time so that λ=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-271A will be stored when the long-term trim must be adjusted to almost maximum in the lower part load area.
Substitute value
none
Possible source
Upper limit:
-intake air leakage
-exhaust system air leakage
-low fuel pressure
-defective heated oxygen sensor (HO2S)
My 2001 s80 2.9l had the same thing , changed the air filter (pretty blocked) and cleaned the air mass sensor with non-chlorinated brake cleaner.
CEL (check engine light) should go off after 5 or 6 complete start and go cycles but the codes will reamain in the computer till you erase them with a scanner.
Hope it helps !
By the way this text comes from my Vadis software .
Carl