Dear Fellow Brickboarders,

Hope you're well. Am I right to conclude that consistent high idle (1,700 rpm) and poor fuel mileage (16-17/U.S. gallon vs. 21 [normal]) might result from a failed throttle position switch? Or, could the engine control unit (ECU) also have failed?

I've replaced: (a) the Idle Air Control Valve (IACV) with a known-good used unit, (b) the engine coolant temperature sensor, (c) the air intake temp sensor; and (d) the MAP (manifold absolute pressure) sensor. The only code is for 1-2-2, which indicated air intake temp sensor's signal was missing or faulty.

The in-service throttle position switch is factory-original, so doesn't owe me a nickel. The same is true of the ECU.

Now, I see a "check engine light" (CEL) on and after start-up. This is new. Only once has the CEL stayed-on after start-up. That was due to failed oxygen sensor.

I appreciate whatever pointers you deem helpful.

Yours faithfully,

Spook