P1401moderate severityPowertrain
DPFE Sensor Circuit High Input
on 2021 Mazda Mazda3 2.0L I4 · AWD
What this code means
The DPFE sensor circuit is reading above the maximum expected voltage. The sensor is reporting excessive EGR flow or has an electrical fault producing a high reading.
Symptoms
- Check Engine Light
- Rough idle
- Engine surge
- Poor fuel economy
- Knocking or pinging
- Failed emissions test
Common causes
- Faulty DPFE sensor corroded internally
- DPFE sensor hoses reversed
- Clogged EGR metering orifice
- Wiring short to power
- Vacuum leak in EGR system
Diagnostic steps
- Check DPFE sensor voltage at key-on engine-off (should be 0.45-0.55V; above 1V indicates bad sensor)
- Verify DPFE hoses are not reversed
- Inspect EGR metering orifice for blockage
- Check wiring for shorts to power
- Test sensor response to applied vacuum
Repair notes
Replace the DPFE sensor, which is the most common cause; verify hoses are correctly connected.
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