Blocked or restricted reference orifice, or its filter, in the leak detection pump or module (design varies by model); Blocked or kinked vent line, or a clogged vent filter or dust filter; Faulty leak detection pump, vent valve or changeover valve that does not move properly; Damaged, split or disconnected EVAP hose or pipe near the module; Wiring or connector fault, such as corrosion, chafing or a poor earth, affecting the pump or valve; Water, dirt or insects blocking the vent path or the module; Faulty control unit or outdated software where a known fault exists for that model.

P043E

EVAP System Leak Detection Reference Orifice Low Flow.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
4: AreaAuxiliary emission controls
3E: FaultThe specific fault in that area

What it means

P043E is the generic code for low flow through the EVAP system's leak detection reference orifice. During the self-test, the control unit checks the pressure or vacuum change across a calibrated reference orifice of known size. When the reading shows less flow than expected, it concludes the orifice or its flow path is restricted or the test is not behaving correctly, and it sets the code.

Symptoms

Engine warning light on
Usually no change in how the car drives
Possible fuel smell around the rear of the car or the engine bay
Failed emissions test or readiness monitor for the EVAP system not completing
Other EVAP codes stored alongside it, such as small leak or purge or vent valve faults

Possible causes

Blocked or restricted reference orifice, or its filter, in the leak detection pump or module (design varies by model)likely
Blocked or kinked vent line, or a clogged vent filter or dust filterlikely
Faulty leak detection pump, vent valve or changeover valve that does not move properlypossible
Damaged, split or disconnected EVAP hose or pipe near the modulepossible
Wiring or connector fault, such as corrosion, chafing or a poor earth, affecting the pump or valvepossible
Water, dirt or insects blocking the vent path or the modulerare
Faulty control unit or outdated software where a known fault exists for that modelrare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting any other EVAP codes and the fuel level and temperature at the time
Check the fuel filler cap is fitted correctly, in good condition and the right type, then look at the filler neck seal
Visually inspect the EVAP hoses, pipes, vent line and connectors around the module, canister and fuel tank for damage, kinks, dirt or disconnection
Inspect the wiring and connector of the leak detection pump or vent valve for corrosion, water ingress and damage
Check the vent filter and the vent path for blockage, using the manufacturer's access procedure for that model
Use a scan tool that supports bidirectional tests to command the pump or vent valve and confirm that it operates and the readings respond
Test the electrical supply, earth and signal to the module or valve against the manufacturer's wiring data
Check for technical service bulletins or software updates for the specific model and engine before replacing parts

How to fix

Clear the blockage in the vent line or filter, or replace the filter if it is clogged
Replace the leak detection pump, module or reference orifice assembly if it is restricted or faulty, following the model-specific procedure
Replace the faulty vent valve or changeover valve
Repair or replace damaged, kinked or disconnected EVAP hoses and pipes
Repair wiring or connector faults, including corrosion and poor earths
Install the manufacturer's updated software only where a known fault for that model calls for it

Can I keep driving?

Low severity

The car can normally be driven as usual, since this fault affects the evaporative emissions system rather than engine running. Book it in soon to stop the light staying on, avoid fuel vapour release and pass an emissions test.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.