What Does P1172 Mean?
This code indicates the second throttle actuation potentiometer signal is too low, falling below the minimum voltage threshold expected by the PCM. In a dual-track throttle position sensing system, a low signal on the secondary track may indicate a short to ground, an open in the 5V reference, or a mechanical fault preventing the potentiometer wiper from reaching its proper voltage range. The PCM may disable or limit electronic throttle control as a safety measure.
Safety Warning
The vehicle will likely enter limp mode with severely restricted throttle response. Driving in limp mode is possible but dangerous in situations requiring sudden acceleration. The vehicle should be repaired before regular driving.
Common Causes
30%
TPS 2 signal wire shorted to ground due to wiring damage
25%
Open or high-resistance 5V reference supply to TPS 2
20%
Failed throttle position potentiometer 2 within the throttle body
15%
Corroded or water-damaged connector at the throttle body
10%
PCM internal pull-down fault on the TPS 2 input circuit
Diagnostic Steps
1
Read TPS 2 voltage in live data; a fixed reading near 0V or below the manufacturer's minimum threshold (typically 0.2-0.5V) confirms the low signal condition.
2
Back-probe the TPS 2 signal wire at the throttle body connector and measure voltage with the key on; compare to TPS 1 to establish baseline.
3
Check for 5V reference voltage at the throttle body connector on the TPS 2 reference pin; if missing, trace the 5V supply back to the PCM.
4
Inspect the connector for corrosion, moisture, or pin damage; verify proper terminal tension.
5
If the 5V reference and ground are present but the signal is low, the throttle body assembly likely needs replacement.
Estimated Repair Cost
$200 - $700
Parts + labor, varies by vehicle and location
This code indicates the second throttle actuation potentiometer signal is too low, falling below the minimum voltage threshold expected by the PCM. In a dual-track throttle position sensing system, a low signal on the secondary track may indicate a short to ground, an open in the 5V reference, or a ...
The most common cause of P1172 (Throttle Actuation Potentiometer Sign. 2 Signal Too Low) is: TPS 2 signal wire shorted to ground due to wiring damage
Typical repair costs for P1172 range from $200 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle will likely enter limp mode with severely restricted throttle response. Driving in limp mode is possible but dangerous in situations requiring sudden acceleration. The vehicle should be repaired before regular driving.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1172 to identify the root cause.
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Quick Info
Category
Powertrain
System
Electronic Throttle Control
Difficulty
Type
Manufacturer
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