How to Diagnose DTC P0193?
Every repair shop is different, and every technician has their own way of working. That said, we recommend following these steps to diagnose the fault code P0193 in your vehicle to pinpoint and fix the problem effectively:
- The first step for any technician is to inspect all wiring and connectors for melting, breaks, worn insulation, or corrosion. In many cases, repairing or replacing damaged wires or connectors resolves numerous issues with poor vehicle performance or the check engine light.
- The technician will then connect an OBD-II scanner to retrieve freeze frame data and stored fault codes in the powertrain control module.
- After reading the codes, the technician will take the vehicle for a test drive to check for the same symptoms you described when dropping off the car. Upon return, they will clear the codes and see if P0193 reappears.
- If P0193 does not immediately reappear during the re-scan, the issue may be intermittent. You might need to adopt a "wait-and-see" approach to determine if the problem worsens and helps identify the root cause of the code.
For cars that fail to start, there’s always a chance the fuel tank is empty, regardless of what the fuel gauge indicates. Most technicians use a fuel pressure gauge to check the fuel pressure. If the reading is low, the vehicle may be out of fuel. If that’s not the issue, the next step would be to check the fuel pump.
The first step in inspecting the fuel pump is simply listening for its operation when the vehicle is cranked. If the car won’t start, but the fuel pump engages, the problem is likely electrical.
If the vehicle doesn’t start and the fuel pump doesn’t run, the technician might attempt to start the car while someone taps the bottom of the fuel tank. If the car starts, it means the fuel pump needs replacement.
Finally, if the car won’t start, the technician will use a multimeter to check the voltage at the fuel pump connector. If there is no voltage at the connector, the technician will inspect the fuse circuit, pump relay circuit, and powertrain control module for faults or short circuits.
If all connections to the battery and powertrain control module are intact, the technician will inspect the fuel rail pressure sensor. Using a multimeter again, they’ll test the sensor’s reference voltage during vehicle operation. It should be 5 volts. If the sensor reads 5 volts, the next step is to inspect the ground wire.
Ready to test the sensor circuit and ground? Your technician will switch the multimeter to ohms and verify that the sensor's resistance readings match the manufacturer’s specifications. If the resistance is out of range, it means the sensor is faulty and needs replacement.
Lastly, if everything functions properly and tests correctly but the problem persists, the powertrain control module may be faulty. This is an expensive replacement and reprogramming process, so ensure all other components are thoroughly checked before determining this as the cause.
