Turbo inlet temperature sensor low
The signal is pinned low — usually the signal wire touching ground, or the 5 V reference lost.
SPN 1172 — Turbo inlet temperature sensor low
SPN 1172 is the parameter the ECM is flagging on International engines. The FMI that comes with it tells you how it failed. Each failure mode below has its own causes and its own test order — do not treat them as the same repair.
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