How is fault code P1400 fixed?

- With the key on and the engine off, read the DPFE voltage in live data: a very low value points to a lost reference or a shorted signal - Inspect both hoses to the sensor for cracks, soot blockage and heat damage - Check for 5 volts on the reference pin and a clean ground at the connector - Inspect the harness where it passes near hot exhaust components - Compare the sensor output at rest against the specified value - Replace the DPFE sensor if reference and ground are correct but the output stays low - Clean or replace a blocked EGR tube or metering orifice, then confirm EGR flow in live data

DPFE Circuit Low Input

Jump to the fix

Severity

Medium

Can I keep driving?

Usually drivable, but get it diagnosed without delay.

First step

With the key on and the engine off, read the DPFE voltage in live data: a very low value points to a lost reference or a shorted signal

PPowertrain
1Manufacturer-specific
4Powertrain (Other)
00Sequence number

What does it mean?

P1400 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: DPFE Sensor Circuit Low Input .

Symptoms

MIL on
Rough idle or a stumble just off idle
Hesitation and light surging while cruising
Slightly higher fuel consumption
Pinging under load because exhaust gas recirculation flow is incorrect
Emissions test failure

Likely causes

Open circuit or short to ground in the DPFE signal wire
Missing 5 volt reference or a lost sensor ground
Failed DPFE sensor, its internal element corroded by exhaust condensate
Disconnected, split or melted DPFE hoses
Corroded or water damaged connector at the sensor
Harness routed too close to the exhaust manifold and heat damaged
Control module input circuit fault

How to fix it

With the key on and the engine off, read the DPFE voltage in live data: a very low value points to a lost reference or a shorted signal
Inspect both hoses to the sensor for cracks, soot blockage and heat damage
Check for 5 volts on the reference pin and a clean ground at the connector
Inspect the harness where it passes near hot exhaust components
Compare the sensor output at rest against the specified value
Replace the DPFE sensor if reference and ground are correct but the output stays low
Clean or replace a blocked EGR tube or metering orifice, then confirm EGR flow in live data

Codes From the Same System

All Fault Codes

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This information follows the generic OBD-II definition and does not replace a vehicle-specific diagnosis. The severity rating is rule-based; an authorised diagnostic reading is required for a definitive answer.