What Does P043E Mean?
The evaporative emission (EVAP) system leak detection pump's reference orifice is showing lower flow than expected. During the EVAP system self-test, the PCM uses a reference orifice of known size to calibrate the leak detection measurement. Low flow through this orifice indicates the leak detection system itself may be compromised, making it unable to accurately test for EVAP leaks. The driver will see the MIL but will not notice any driveability symptoms.
Common Causes
35%
Clogged or restricted reference orifice in the leak detection pump
25%
Weak or failing leak detection pump motor
20%
Blocked or kinked hose between the leak detection pump and reference orifice
12%
Contamination or debris in the EVAP system blocking airflow
8%
Electrical issue reducing pump motor speed
Diagnostic Steps
1
Run the EVAP leak detection self-test via the scan tool and monitor the pump pressure/flow parameters — compare reference orifice flow readings to manufacturer specifications.
2
Inspect the leak detection pump assembly for damage, contamination, or water ingress — these pumps are typically mounted low on the vehicle and prone to road debris and moisture.
3
Check the EVAP system vent filter (usually near the charcoal canister) for clogging — a restricted vent filter will reduce flow through the entire leak detection system.
4
Measure the voltage and current to the leak detection pump motor during operation — low voltage or high current draw can indicate a failing motor or restricted system.
5
Inspect all EVAP hoses connected to the leak detection pump for kinks, collapse, or blockage.
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
The evaporative emission (EVAP) system leak detection pump's reference orifice is showing lower flow than expected. During the EVAP system self-test, the PCM uses a reference orifice of known size to calibrate the leak detection measurement. Low flow through this orifice indicates the leak detection...
The most common cause of P043E (Evaporative Emission System Leak Detection Reference Orifice Low Flow) is: Clogged or restricted reference orifice in the leak detection pump
Typical repair costs for P043E range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. This code indicates the EVAP leak detection system cannot properly self-test. There is no performance or safety risk. The vehicle may fail emissions testing.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P043E to identify the root cause.
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Quick Info
Category
Powertrain
System
Evaporative Emission (EVAP) System
Difficulty
Type
Generic (SAE)
Recommended Tools
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