What Does P1123 Mean?
P1123 indicates the Throttle Position Sensor signal is within its valid operating range but is reading higher than the ECM expects based on other engine operating parameters. The TPS is not outright failing, but its reported angle is inconsistent with the commanded throttle position, idle speed control state, or accelerator pedal position. This suggests a calibration issue, mechanical binding, or sensor offset.
Common Causes
30%
TPS out of calibration or base voltage set too high (closed throttle voltage above specification)
25%
Carbon buildup holding the throttle plate slightly open
18%
Throttle cable or linkage adjusted too tight preventing full closure
15%
Aftermarket air filter or intake modification affecting throttle position at idle
12%
TPS sensor internally shifted, outputting a higher voltage than actual position
Diagnostic Steps
1
Step 1: Read TPS voltage at closed throttle with the key on, engine off. Typical specification is 0.4–0.8V. A reading above 1.0V at closed throttle suggests the sensor is reading higher than expected.
2
Step 2: Inspect the throttle body for carbon deposits holding the blade slightly open. Clean the throttle body with throttle body cleaner and ensure the plate closes fully.
3
Step 3: Check the throttle cable or linkage for proper adjustment. There should be slight free play — if the cable is pulling the throttle open even slightly, the TPS will read high.
4
Step 4: If the TPS is adjustable, loosen the mounting screws and rotate the sensor until the closed-throttle voltage is within specification, then retighten.
5
Step 5: For electronic throttle control systems, perform a TPS relearn procedure using the scan tool after cleaning the throttle body. This recalibrates the ECM to the sensor's actual range.
Estimated Repair Cost
$20 - $300
Parts + labor, varies by vehicle and location
P1123 indicates the Throttle Position Sensor signal is within its valid operating range but is reading higher than the ECM expects based on other engine operating parameters. The TPS is not outright failing, but its reported angle is inconsistent with the commanded throttle position, idle speed cont...
The most common cause of P1123 (Throttle Position Sensor In Range But Higher Than Expected) is: TPS out of calibration or base voltage set too high (closed throttle voltage above specification)
Typical repair costs for P1123 range from $20 to $300, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A TPS reading higher than expected can cause elevated idle speed, delayed downshifts on automatic transmissions, and incorrect fuel delivery. While not immediately dangerous, the engine may behave unpredictably at low speeds.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1123 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Management / Throttle Control
Difficulty
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