What Does P043F Mean?
The evaporative emission (EVAP) leak detection pump's reference orifice is allowing higher flow than expected during the system self-test. The reference orifice is a calibrated opening used to benchmark leak detection measurements, and excessive flow suggests the orifice is enlarged, damaged, or bypassed. This compromises the accuracy of EVAP leak testing. The driver will see the MIL but will experience no driveability symptoms.
Common Causes
35%
Damaged or enlarged reference orifice in the leak detection pump
25%
Cracked or leaking hose at the reference orifice connection
20%
Leak detection pump internal seal failure allowing bypass flow
12%
Loose connection at the reference orifice fitting
8%
Incorrect leak detection pump replacement part with wrong orifice size
Diagnostic Steps
1
Run the EVAP system self-test via the scan tool and record the reference orifice flow parameters — compare to manufacturer's specification for normal reference flow range.
2
Inspect the leak detection pump assembly for physical damage, cracking, or obvious air leaks around the reference orifice area.
3
Check all hose connections at the leak detection pump for security and integrity — apply soapy water while the pump is running and look for bubbles indicating air leaks.
4
Verify the correct leak detection pump part number is installed — incorrect replacement pumps may have different reference orifice calibrations.
5
If the pump was recently replaced, ensure all seals and O-rings were properly installed and the assembly is fully seated.
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
The evaporative emission (EVAP) leak detection pump's reference orifice is allowing higher flow than expected during the system self-test. The reference orifice is a calibrated opening used to benchmark leak detection measurements, and excessive flow suggests the orifice is enlarged, damaged, or byp...
The most common cause of P043F (Evaporative Emission System Leak Detection Reference Orifice High Flow) is: Damaged or enlarged reference orifice in the leak detection pump
Typical repair costs for P043F range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. The EVAP leak detection calibration is compromised but this does not affect engine performance, fuel delivery, or vehicle safety. Required for emissions compliance.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P043F to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Evaporative Emission (EVAP) System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
