P1670: EF Signal Not Detected
The P1670 code indicates that the Engine Control Module (ECM) has not detected the expected signal from the electronic fuel (EF) system, typically related to the fuel pump or fuel pressure sensor. This can be caused by a faulty fuel pump relay, wiring issues, a defective fuel pump, or a malfunctioning fuel pressure sensor. The ECM relies on this signal to ensure proper fuel delivery; without it, the engine may not start or may run poorly.
01. Most Common Causes
- Faulty fuel pump relay
- Open or shorted wiring in the fuel pump circuit
- Defective fuel pump
- Malfunctioning fuel pressure sensor
02. Symptoms You Will Notice
- Engine cranks but does not start
- Engine stalls shortly after starting
- Loss of power during acceleration
- Check Engine Light illuminated
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P1670 and check for other codes.
Step 2: Inspect the fuel pump relay and fuse; test for power and ground at the relay.
Step 3: Check wiring and connectors between the ECM and fuel pump for damage or corrosion.
Step 4: Test fuel pump operation by listening for prime when key is turned on; if no sound, test pump voltage and ground.
Step 5: If pump runs, test fuel pressure with a gauge; if low, replace pump or pressure regulator.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
No, it is not safe. The vehicle may stall unexpectedly or fail to start, leading to a breakdown or accident.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, depending on whether the issue is a relay, wiring, or fuel pump replacement.