P1405 EGR DPFE Sensor Low Voltage
The P1405 code indicates that the EGR Differential Pressure Feedback (DPFE) sensor circuit voltage is below the expected operating range. The Powertrain Control Module (PCM) detects a signal voltage lower than 0.5 volts, preventing accurate measurement of the pressure drop across the EGR system. This sensor monitors the pressure difference between two tap tubes located before and after a restriction in the exhaust pipe, allowing the PCM to calculate EGR flow. A low voltage signal points to an electrical fault in the sensor circuit or a failed internal sensor.
01. Most Common Causes
- Faulty or internally failed DPFE sensor
- Short to ground in the sensor signal wire
- Open circuit in the sensor power (VREF) or ground wire
- Corroded, damaged, or loose electrical connector at the sensor
- Internal PCM failure (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Rough idle or hesitation during acceleration
- Poor fuel economy
- Failed emissions test due to increased NOx
03. Step-by-Step Diagnosis
Scan for codes and verify P1405 is present; check for other related codes.
Visually inspect the DPFE sensor connector and wiring for corrosion, damage, or loose connections.
With key on engine off, measure voltage at the DPFE sensor signal wire (should be around 0.5-1.0V at rest). If below 0.5V, suspect a short to ground or faulty sensor.
Check reference voltage (VREF) at the sensor connector (typically 5V). If missing, check for open circuit or PCM issue.
If wiring and voltage checks are normal, replace the DPFE sensor and clear codes; retest.
1. Frequently Asked Questions
Is it safe to drive?▼
Yes, but you may experience reduced performance and fuel economy. Prolonged driving can lead to increased emissions and potential damage to the EGR system. It's best to diagnose and repair soon.
How much does it cost to fix?▼
Typically $100 to $300, including parts (DPFE sensor $40-$120) and labor (1-2 hours at $80-$150 per hour).