What Does P1173 Mean?
This code indicates the second throttle actuation potentiometer signal is too high, exceeding the maximum voltage threshold expected by the PCM. The signal is pulled toward or above the 5V reference, suggesting a short to the reference voltage, an open ground circuit, or an internal potentiometer fault. The PCM will recognize the inconsistency with the primary TPS and may activate failsafe reduced-power mode to protect against unintended throttle opening.
Safety Warning
A TPS signal stuck high may cause the PCM to interpret unintended wide-open throttle, triggering immediate failsafe mode. In rare cases where failsafe does not activate properly, unintended acceleration could occur. This is a critical safety code requiring prompt repair.
Common Causes
30%
TPS 2 signal wire shorted to the 5V reference wire in the harness
25%
Open or high-resistance ground circuit for TPS 2
20%
Failed throttle position potentiometer 2 (internal short to reference)
15%
Connector terminal damage allowing signal and reference pins to contact
10%
Aftermarket throttle body or sensor with incorrect resistance/output range
Diagnostic Steps
1
Read TPS 2 voltage in live data; a fixed reading near 5V or above the manufacturer's maximum threshold (typically 4.5-4.8V at wide-open throttle) confirms the high signal condition.
2
With the throttle closed, TPS 2 should read approximately 0.5-1.0V (manufacturer-dependent); if it reads above 4V at closed throttle, a fault is confirmed.
3
Disconnect the throttle body connector and measure resistance between the TPS 2 signal pin and the ground pin; compare to specification.
4
Check for an open ground wire by measuring resistance from the throttle body ground pin to a known-good engine ground.
5
Inspect for chafed wiring where the TPS signal wire and 5V reference wire run together; separate and repair if shorted.
6
Replace the throttle body assembly if internal potentiometer fault is confirmed.
Estimated Repair Cost
$200 - $700
Parts + labor, varies by vehicle and location
This code indicates the second throttle actuation potentiometer signal is too high, exceeding the maximum voltage threshold expected by the PCM. The signal is pulled toward or above the 5V reference, suggesting a short to the reference voltage, an open ground circuit, or an internal potentiometer fa...
The most common cause of P1173 (Throttle Actuation Potentiometer Sign. 2 Signal Too High) is: TPS 2 signal wire shorted to the 5V reference wire in the harness
Typical repair costs for P1173 range from $200 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A TPS signal stuck high may cause the PCM to interpret unintended wide-open throttle, triggering immediate failsafe mode. In rare cases where failsafe does not activate properly, unintended acceleration could occur. This is a critical safety code requiring prompt repair.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1173 to identify the root cause.
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Quick Info
Category
Powertrain
System
Electronic Throttle Control
Difficulty
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