P043E - Evaporative Emission (EVAP) System Reference Orifice Low Flow
Last updated:
System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
Code P043E is stored when the Engine Control Unit (ECU) detects that the flow through the EVAP system's reference orifice is lower than a pre-defined threshold during a leak detection pump (LDP) diagnostic cycle. The system performs a 'vacuum pull-down' or pressure test. If the orifice, which serves as a baseline comparison for the system's integrity, is restricted or clogged (often by moisture, dust, or spiders/insects), the pump's amperage draw deviates from the calibrated norm, triggering the fault code.
Possible Causes
Clogged filter or reference orifice within the charcoal canister/vent assembly
Blocked, pinched, or kinked EVAP vent hose VIDA.
Faulty Leak Detection Pump (LDP) with internal mechanical restriction
Damaged wiring or corrosion in the electrical connector to the pump
Symptoms
Recommended Solution
- Perform a visual inspection of all EVAP vent hoses and the charcoal canister. Look for kinks, cracks, or debris (spider nests are common in vent tubes).
- Remove the reference filter or vent valve and check for obstructions. Blow through it gently with low-pressure air to ensure it is clear.
- Use a scan tool to command the Leak Detection Pump (LDP) to run. Monitor pump current (Amps) – it should typically be between 20-100 mA during the reference check phase.
- Verify 12V power supply and ground at the LDP connector. Check signal wire continuity to the ECU (resistance should be less than 5 Ohms).
- If filters and hoses are clear but the code persists, replace the Leak Detection Pump or the integrated charcoal canister assembly.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
Do you also have
other fault codes?
See how P043E connects with your other fault codes. Our advanced analysis tool identifies causal relationships and root causes directly.