P1400moderate severityPowertrain
DPFE Sensor Circuit Low Input
on 1999 Mazda MX-5 Miata 1.8L I4 · RWD
What this code means
The Differential Pressure Feedback EGR sensor circuit is reading below the minimum expected voltage. The DPFE sensor measures exhaust gas flow through the EGR valve by detecting a pressure differential.
Symptoms
- Check Engine Light
- Rough idle
- Stalling
- Poor fuel economy
- Failed emissions test
Common causes
- Faulty DPFE sensor (most common)
- Clogged DPFE sensor hoses
- Wiring short to ground
- Corroded DPFE sensor from moisture
- EGR passage blockage
Diagnostic steps
- Check DPFE sensor voltage at key-on engine-off (should be 0.45-0.55V)
- Inspect DPFE sensor hoses for cracks or blockage
- Test DPFE sensor wiring for shorts
- Check for carbon buildup in EGR passages
- Replace DPFE sensor and retest
Repair notes
Replace the DPFE sensor, which commonly fails from moisture corrosion; inspect and clean EGR passages.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1