Diagnostic trouble code P1173 is a manufacturer-specific powertrain fault code. Because it is manufacturer-specific, its exact definition depends entirely on the vehicle make, model, and application.
Exact vehicle application must be verified before diagnosis. The code identifies a detected condition in a specific subsystem, but further testing is required to identify the root cause.
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Key Takeaways
- P1173 is a manufacturer-specific code, meaning its definition varies significantly between automakers like Volkswagen, Audi, Mazda, and Land Rover.
- On VW and Audi applications, it indicates a throttle actuation potentiometer signal 2 circuit reading too high.
- On Mazda and Land Rover applications, it points to a front heated oxygen sensor (Bank 2 Sensor 1) failing to switch or invert.
- Diagnosis requires verifying the exact factory definition and testing the relevant throttle or oxygen sensor circuits.
P1173 Code Description and Implications
Because P1173 is manufacturer-specific, there is no single universal definition. This trouble code identifies a detected condition, but the exact monitored system depends on the vehicle make and model.
Some Volkswagen and Audi applications: P1173 indicates a “Throttle Actuation Potentiometer Signal 2 Signal Too High” fault. The engine control module detects that the voltage from the secondary throttle position sensor is above the expected maximum range.
Some Mazda and Land Rover applications: P1173 indicates a “Front Heated Oxygen Sensor No Inversion” or non-switching condition. The module detects that the Bank 2 Sensor 1 oxygen sensor signal remains static and fails to switch between rich and lean.
Common Causes of the P1173 Code
For VW and Audi applications, possible causes include a failing throttle body assembly, damaged wiring in the throttle position sensor circuit, poor electrical connections, or a failing engine control module.
For Mazda and Land Rover applications, causes may involve a failing front heated oxygen sensor, exhaust leaks near the sensor, damaged sensor wiring, or fuel system issues like a leaking fuel injector altering the exhaust mixture.
Symptoms Associated With P1173
On VW and Audi applications with a throttle position fault, symptoms can include reduced engine power, limp mode activation, rough idling, and an illuminated Check Engine Light.
On Mazda and Land Rover applications with an oxygen sensor fault, symptoms may include decreased fuel efficiency, rough idling, engine misfires, and an illuminated Check Engine Light.
Diagnosing the P1173 Trouble Code
Diagnosis must begin by confirming the exact factory definition for the specific make, model, and year.
For VW and Audi applications, technicians inspect the throttle body connector, test the secondary throttle position sensor signal circuit for shorts to voltage, and verify the sensor operation using live data.
For Mazda and Land Rover applications, technicians inspect the exhaust manifold for leaks, test the oxygen sensor heater and signal circuits, and monitor the sensor switching activity using a scan tool.
Repairing the P1173 Issue
If a throttle position fault is confirmed on a VW or Audi application, the throttle body assembly or the damaged wiring harness must be replaced or repaired, followed by a throttle adaptation.
If an oxygen sensor fault is confirmed on a Mazda or Land Rover application, the exhaust leak must be repaired, or the confirmed failed Bank 2 Sensor 1 oxygen sensor must be replaced.
Cost Considerations for P1173 Repairs
Cost depends on diagnostic time, component accessibility, required parts, programming requirements, and labor.
Replacing an oxygen sensor involves minimal labor but requires clearing codes and verifying monitor completion.
Replacing a throttle body assembly requires component replacement and specific adaptation procedures using a scan tool.
Prevention Strategies for Future Occurrences
Some electrical and mechanical failures cannot be reliably prevented.
Inspecting exposed engine wiring harnesses for chafing or heat damage can help prevent electrical faults in throttle or sensor circuits.
Addressing exhaust leaks and maintaining the fuel system can help protect oxygen sensors from contamination and premature failure.
Troubleshooting Tips and Best Practices
Never assume P1173 is a universal oxygen sensor code. Always verify the exact definition for the specific vehicle before purchasing parts.
Do not ignore related codes. A throttle position fault may appear alongside other throttle actuator codes, while an oxygen sensor fault may appear alongside fuel trim or catalyst efficiency codes.
Check for technical service bulletins applicable to your exact vehicle application, as manufacturers frequently release updated sensors or revised software calibrations for recurring faults.
More OBD-II Codes
| P1172 | P1174 | P0131 | P1186 |
| P1171 | P1175 | P0132 | P1187 |
| P1170 | P1176 | P0133 | P1188 |
| P1168 | P1178 | P0137 | P1189 |
| P1167 | P1180 | P0138 | P1190 |
| P1166 | P1185 | P0140 | P1191 |
Frequently Asked Questions
Is P1173 a generic or manufacturer-specific code?
No. P1173 is a manufacturer-specific code. Its exact definition varies significantly between automakers, so the factory service information for the specific vehicle must be consulted.
Can I drive my car with a P1173 code?
It depends on the application. If P1173 indicates a throttle position fault, the vehicle may enter limp mode. If it is an oxygen sensor fault, fuel efficiency may drop.
Will disconnecting the battery clear the P1173 code?
Disconnecting the battery may temporarily clear the code, but it does not repair the underlying electrical or mechanical fault. It also resets readiness monitors and throttle adaptations.
Can an exhaust leak cause a P1173 code?
Yes. On Mazda and Land Rover applications, an exhaust leak upstream of the oxygen sensor can introduce false air, preventing the sensor from switching properly and triggering the code.
Does P1173 always mean the oxygen sensor is bad?
No. While a failing oxygen sensor is a cause on specific applications, the code can also indicate a throttle position sensor fault on VW and Audi vehicles, or damaged wiring.
What Should You Do About the P1173 Code?
Confirm the exact factory definition and diagnostic procedure for your specific vehicle application. Because P1173 is manufacturer-specific, identifying whether it relates to a throttle actuation potentiometer circuit or a heated oxygen sensor is mandatory.
Follow the applicable manufacturer diagnostic steps to test the relevant system and components. Once the root cause is confirmed, complete the necessary repairs and verify that the system operates correctly and the code does not return.
