What Does P1122 Mean?
P1122 indicates the Throttle Position (TP) sensor circuit is intermittently producing a voltage below the expected range. The ECM detects the throttle position signal dropping to near 0V sporadically, which it interprets as a closed or nearly-closed throttle when the actual position may be different. This can cause sudden torque reduction, idle hunting, and erratic transmission shift behavior on automatic vehicles.
Safety Warning
Intermittent TPS faults can cause sudden and unexpected changes in engine power output. The ECM may enter failsafe mode with severely limited throttle response, which is dangerous if it occurs during highway driving or passing maneuvers.
Common Causes
30%
Worn TPS with intermittent dead spot in the resistive element
25%
Loose or corroded TP sensor connector
20%
Intermittent open or short to ground in the TPS signal wire
15%
5V reference circuit dropping out from shared sensor overload
10%
TPS mounting screws loose causing sensor movement relative to throttle shaft
Diagnostic Steps
1
Step 1: Monitor TPS voltage while slowly sweeping the throttle from closed to open. Watch for any sudden voltage drops or dead spots that indicate a worn resistive element.
2
Step 2: Wiggle the TPS connector and wiring while monitoring the voltage. Dropouts during the wiggle test indicate a connection fault.
3
Step 3: Verify the 5V reference and ground are present and stable at the TPS connector. If the reference voltage drops out intermittently, check other sensors on the shared 5V circuit.
4
Step 4: Inspect TPS mounting. If the sensor is not firmly secured to the throttle body, it can shift position intermittently, causing signal variations that do not correspond to actual throttle movement.
5
Step 5: Replace the TPS if the sensor exhibits dead spots or erratic output. On electronic throttle bodies with integrated TPS, the entire throttle body may need replacement.
Estimated Repair Cost
$50 - $400
Parts + labor, varies by vehicle and location
P1122 indicates the Throttle Position (TP) sensor circuit is intermittently producing a voltage below the expected range. The ECM detects the throttle position signal dropping to near 0V sporadically, which it interprets as a closed or nearly-closed throttle when the actual position may be different...
The most common cause of P1122 (Throttle Position (TP) Sensor Circuit Intermittent Low Voltage) is: Worn TPS with intermittent dead spot in the resistive element
Typical repair costs for P1122 range from $50 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Intermittent TPS faults can cause sudden and unexpected changes in engine power output. The ECM may enter failsafe mode with severely limited throttle response, which is dangerous if it occurs during highway driving or passing maneuvers.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1122 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Management / Throttle Control
Difficulty
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