Throttle position sensor high
The signal wire is seeing more voltage than the circuit should ever produce — usually the signal wire touching battery power or the 5 V reference.
SPN 91 — Throttle position sensor high
SPN 91 is the parameter the ECM is flagging on CAT 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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