Fuel Pump Secondary Circuit Intermittent
Your car's backup fuel pump (usually in the tank) is losing electrical connection on and off, like a flickering light switch. The engine computer detects this intermittent signal dropout and logs the fault.
The ECM monitors the secondary fuel pump relay circuit voltage and current draw during operation. It expects stable voltage supply and continuous current flow when the pump should be running. If the signal drops below threshold intermittently without the ignition being cycled, the fault is recorded.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Secondary Pump Voltage | 12V steady during fuel demand | Voltage drops below 10.5V intermittently or signal lost |
| Pump Current Draw | 2-6 amps continuous | Erratic current spikes or drops indicating connection loss |
Code P0234 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0234 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.