The P1189 trouble code is a manufacturer-specific powertrain code. Its exact definition depends entirely on the vehicle application, primarily indicating a fuel pump speed signal fault, a fuel control issue, or an engine oil pressure switch circuit malfunction.
Because it is manufacturer-specific, the exact application must be verified. The code identifies a detected condition, and testing is required to identify the root cause before replacing any components.
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Key Takeaways
- P1189 is a manufacturer-specific code with definitions varying significantly between automakers.
- On Ford applications, it indicates a fuel pump speed signal fault.
- On BMW applications, it points to a fuel control malfunction for Bank 2 Sensor 1.
- On General Motors applications, it indicates an engine oil pressure switch circuit issue.
- Proper diagnosis requires verifying the exact factory definition and testing the relevant circuits.
P1189 Code Description and Implications
The P1189 code is a manufacturer-specific powertrain definition. Because it is not a generic SAE code, its exact meaning depends entirely on the vehicle application.
Ford applications: P1189 indicates a pump speed signal fault. The powertrain control module detects a missing or erratic signal from the fuel pump speed sensor or feedback circuit.
BMW applications: P1189 indicates a fuel control malfunction for Bank 2 Sensor 1. The engine control module detects that the air-fuel mixture compensation is outside the expected range.
General Motors applications: P1189 indicates an engine oil pressure switch circuit malfunction. The control module detects an open or shorted condition in the oil pressure sensor circuit.
Volkswagen and Audi applications: P1189 indicates a linear oxygen sensor compensation resistor short to voltage. The module detects excessive voltage in the sensor compensation circuit.
Common Causes of the P1189 Code
Electrical faults, sensor degradation, and mechanical issues are the primary triggers, though the specific causes vary by manufacturer.
For Ford applications: The issue stems from a failed fuel pump speed sensor, damaged wiring harnesses, or a failing fuel pump assembly.
For BMW applications: The fault is caused by unmetered air entering the intake, a failing oxygen sensor, or a vacuum leak affecting the Bank 2 fuel mixture.
For GM applications: The issue is caused by a failed engine oil pressure switch, an open wire in the sensor circuit, or poor connections at the module.
For VW and Audi applications: The issue is caused by a short to voltage in the linear oxygen sensor wiring or a failed sensor compensation resistor.
Symptoms Associated With P1189
When the control module detects a fault in these specific monitoring systems, it illuminates the Check Engine Light.
Ford applications: You may experience extended cranking times, poor acceleration, or stalling if the control module cannot verify fuel pump operation.
BMW applications: You may experience rough idling, poor fuel economy, or hesitation due to the engine control module struggling to correct the air-fuel mixture on Bank 2.
GM applications: You may not experience drivability symptoms if the code solely indicates an oil pressure switch circuit fault, though the oil pressure warning light may illuminate.
VW and Audi applications: You may experience poor fuel efficiency or failed emissions tests due to the oxygen sensor failing to accurately monitor the exhaust gases.
Diagnosing the P1189 Trouble Code
Accurate diagnosis begins by confirming the exact factory definition for your specific vehicle make and model, as this is a manufacturer-specific trouble code.
Ford diagnosis: Inspect the fuel pump wiring and speed sensor circuit. Use a multimeter or oscilloscope to verify the pump speed signal matches the manufacturer’s expected frequency or voltage pattern.
BMW diagnosis: Perform a smoke test to identify unmetered air entering the intake. Inspect the Bank 2 Sensor 1 oxygen sensor circuit and verify live fuel trim data.
GM diagnosis: Inspect the engine oil pressure switch connector for corrosion or oil intrusion. Measure the sensor circuit for opens or shorts and verify actual engine oil pressure mechanically.
VW and Audi diagnosis: Inspect the linear oxygen sensor wiring for a short to voltage. Measure the compensation resistor circuit to identify electrical faults.
Repairing the P1189 Issue
Repairs must address the specific root cause identified during testing.
Ford repair: If the fuel pump speed sensor fails testing or the pump itself is failing, replace the confirmed failed component. Repair any damaged wiring harnesses.
BMW repair: If a vacuum leak is confirmed, replace the damaged intake boot or vacuum hose. If the oxygen sensor fails testing, replace the confirmed failed sensor.
GM repair: If the engine oil pressure switch fails testing or is leaking oil into the connector, replace the confirmed failed switch and clean the harness.
VW and Audi repair: If the oxygen sensor compensation circuit is shorted to voltage, repair the damaged wiring. If the sensor itself is internally shorted, replace the confirmed failed sensor. Ensure the fuel injector circuits are also functioning correctly, as mixture faults can affect sensor readings.
Cost Considerations for P1189 Repairs
Cost depends on diagnostic time, component accessibility, required parts, programming requirements, and labor.
Replacing an oil pressure switch or oxygen sensor is generally a straightforward repair with moderate parts and labor costs. Replacing a complete fuel pump assembly or performing extensive smoke testing for vacuum leaks may require higher labor times.
Prevention Strategies for Future Occurrences
Inspecting exposed wiring harnesses near the fuel tank or engine bay for early signs of chafing or degradation can help prevent circuit faults from developing.
Keeping electrical connectors clean and ensuring protective seals are intact may reduce moisture intrusion and prevent corrosion-related sensor faults.
Troubleshooting Tips and Best Practices
Do not immediately replace the engine control module just because a P1189 code is present. A failed sensor, a vacuum leak, or a poor connection will produce the exact same fault reading.
Always verify the manufacturer-specific definition first. A code that means a fuel pump speed fault on a Ford means an oil pressure switch issue on a GM vehicle.
Check for Technical Service Bulletins for your specific vehicle. Manufacturers occasionally release updated sensor part numbers or revised wiring harness routing procedures to address chronic circuit issues.
More OBD-II Codes
| P1187 | P1186 | P1185 | P1176 |
| P1175 | P1174 | P1190 | P1191 |
| P1192 | P1193 | P1194 | P1195 |
| P0131 | P0132 | P0133 | P0135 |
| P0137 | P0138 | P0140 | P0141 |
| P1211 | P1212 | P1213 | P1214 |
Frequently Asked Questions
Is P1189 a generic or manufacturer-specific code?
No. P1189 is a manufacturer-specific powertrain code. It indicates a fuel pump speed fault on Ford, a fuel control issue on BMW, and an oil pressure switch fault on GM.
Can I drive my car with a P1189 code?
Driving is not recommended if the code indicates a fuel pump failure or low oil pressure. A failing fuel pump can cause sudden stalling, while ignoring oil pressure issues can cause severe engine damage.
Will disconnecting the battery clear the P1189 code?
Disconnecting the battery may temporarily erase the code, but it will not repair a failed sensor, a vacuum leak, or damaged wiring. The code will return once the monitor runs.
Can a vacuum leak cause a P1189 code on a BMW?
Yes. On applicable BMW applications, P1189 indicates a fuel control malfunction for Bank 2. Unmetered air entering the intake through a vacuum leak frequently causes the mixture compensation to exceed the expected range.
Does P1189 always mean the fuel pump is bad?
No. The code identifies a detected circuit condition. On Ford applications, it may be caused by a failed speed sensor or damaged wiring. Components should only be replaced after testing confirms failure.
What Should You Do About the P1189 Code?
Confirm the exact factory definition for your vehicle, then follow the applicable manufacturer diagnostic procedure. Because P1189 is manufacturer-specific, the diagnostic path for a fuel pump speed fault differs entirely from an oil pressure switch issue.
Inspect the relevant system and components, including fuel pump circuits, oxygen sensors, and oil pressure switches. Repair any confirmed wiring damage, or replace the relevant system components only after testing verifies the failure.
