P043F: EVAP leak-test reference check reads too much flow
EVAP leak detection reference orifice high flow
Severity: Monitor
P043F is an EVAP self-test fault; PartsAvatar describes it as not immediately dangerous, though the emissions system needs prompt diagnosis.
It gets more serious if:
- Inspect soon: Have it looked at sooner if other EVAP codes appear with it or you hear the leak detection pump humming or hissing with the ignition off.
P043F in short
P043F means the computer measured more air flowing through the small reference opening that its EVAP leak-detection pump uses as a yardstick. Likely causes are the leak detection pump or EVAP pressure sensor, a damaged canister or a cracked EVAP line. It is generally safe to drive, but the car will not pass an emissions check.
Some EVAP systems carry a leak detection pump with a tiny precision opening. The computer pulls air through that opening first to learn what a known small leak looks like, then compares the real system against it.
P043F sets when the flow through that reference is higher than expected. Because the yardstick is off, the computer can no longer judge real leaks reliably.
PartsAvatar lists the EVAP pressure sensor, the canister, EVAP and vacuum lines, the leak detection pump and its wiring as the usual suspects.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Leak detection pump or its wiring
Common general cause- Why it ranks here
- PartsAvatar lists the leak detection pump, vacuum pump module and its harness among the main causes, and the code is about that pump's reference check.
- What would change this
- Rises if the pump hums or hisses with the ignition off or its connector is damaged. Falls if the pump and wiring test normal.
Cause 2: EVAP pressure sensor reading wrong
Common general cause- Why it ranks here
- The flow check is judged from the EVAP pressure sensor, and PartsAvatar names it first in its cause list.
- What would change this
- Rises if the sensor reading is off at key-on with the system open. Falls if the reading is plausible.
Cause 3: Damaged canister or cracked EVAP or vacuum lines
Possible — needs testing- Why it ranks here
- PartsAvatar also lists a damaged charcoal canister and cracked or crushed lines.
- What would change this
- Rises if a smoke test or inspection finds damage. Falls if the lines and canister are intact.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Read all stored codes and freeze-frame data and note any other EVAP codes.
IfOther EVAP codes are stored
It meansDiagnose those together; they may share a cause.
IfP043F is alone
It meansInspect the pump module and wiring.
Step 2: Visually inspect the EVAP pump module harness and connectors in hot areas and the EVAP and vacuum lines for damage.
IfDamaged wiring, connector or line is found
It meansRepair it and retest.
IfNothing visible
It meansHave the leak detection pump and pressure sensor tested.
Symptoms
- Check engine light
- Hissing or humming from the leak detection pump with the ignition off
- Failed emissions test
How to fix
Step 1: With the engine off and cool, look over visible EVAP hoses and connectors near the pump for cracks or loose fittings.
On your vehicle
We don't have reviewed vehicle-specific evidence for P043F yet. The causes and tests above apply across vehicles.
Related codes
P043F questions
Can I drive with P043F?
Yes, PartsAvatar describes it as not immediately dangerous, but it will fail an emissions check until fixed.
Sources and review
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error