- Check the ISS sensor circuit
- Replace the ISS sensor
- Repair or replace any short or open in the circuit.
- Replace the PCM
When a Mazda vehicle is experiencing issues, the on-board diagnostics computer may generate a trouble code that points to a specific fault. The P0791 trouble code is one such code, which indicates an issue with the Input Shaft Speed (ISS) Sensor. This fault code is displayed when the Powertrain Control Module (PCM) detects a failure of the ISS Sensor signal. Understanding what this code means and the potential causes and solutions of the issue can help automotive technicians identify the source of the problem and make necessary repairs. The Mazda P0791 Code is marked by a few common causes, such as a damaged or failed ISS Sensor, an open circuit, or a shorted circuit to ground or system power, and a few solutions that automotive technicians can execute to repair the issue, such as replacing the ISS Sensor, repairing any open or short circuits, and replacing the PCM if necessary.
Mazda P0791 Code – Causes and Solutions
| Cause | Solution |
|---|---|
| Input Shaft Speed Sensor circuit is open | Check the ISS sensor circuit |
| ISS circuit is shorted to ground | Replace the ISS sensor |
| ISS circuit is shorted to system power (B+) | Repair or replace any short or open in the circuit. |
| ISS Sensor is damaged or has failed | Replace the PCM |
Checking the ISS Sensor Circuit
When the Mazda P0791 trouble code is generated, the first step is to check the ISS Sensor circuit. This involves checking the wiring harness, connectors, and voltage levels to ensure the circuit is working properly. If the circuit is found to be open, it must be repaired or replaced.
Replacing the ISS Sensor
If the circuit is found to be shorted to ground or system power, the ISS Sensor must be replaced. The ISS Sensor is an important part of the engine’s control system, and replacing it is necessary to ensure the engine is running properly.
Repairing Short or Open Circuits
In some cases, the ISS Sensor circuit may be shorted or open. If this is the case, the circuit must be repaired or replaced. This involves checking for any damaged wiring or connectors, and replacing them if necessary.
Replacing the PCM
If the ISS Sensor is found to be damaged or has failed, the Powertrain Control Module (PCM) must be replaced. Replacing the PCM will ensure that the engine is running properly and that the P0791 trouble code is resolved.
Conclusion
The Mazda P0791 Code is a fault code that indicates a problem with the Input Shaft Speed (ISS) Sensor. The causes of this code are often related to the ISS Sensor circuit, such as open or shorted circuits, a damaged or failed ISS Sensor, and a damaged or failed PCM. Automotive technicians can check the ISS Sensor circuit, replace the ISS Sensor, repair open and shorted circuits, and replace the PCM if necessary to resolve the issue. With the proper diagnostic procedures, automotive technicians can easily identify and repair the issue.
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