P2401 trouble code definition
P2401 is a OBD2 generic trouble code indicating a fault within the EVAP leak detection circuit. This code may be seen with other EVAP system codes.
What the P2401 code means
The P2401 trouble code is telling us the EVAP control circuit has had a fault with the leak detection pump. The leak detection pump is used by the ECM to pressurize the EVAP system to check for leaks that are present.
When the ECM has detected the the circuit has low voltage it will trigger a P2401 code. The code will remain until the issue is resolved or normal voltage is detected over multiple vehicle trips.
What causes the P2401 code?
- Gas cap is faulty
- Charcoal canister failure
- Leaking or cracked fuel vapor lines
- Open or short in the wiring harness
- ECM that has failed or is failing
- Faulty purge control solenoid
- Leak detection pump has failed
What are the symptoms of the P2401 code?
The Check Engine Light will be triggered in all instances of the P2401 code.
Generally no other symptoms are noticed by the driver.
How does a mechanic diagnose the P2401 code?
The P2401 code can be a complex code to diagnose. Following these simple steps technicians are able to diagnose this code:
Hook up a scan tool and check for any codes stored in the ECM
Note all codes and the freeze frame data for each
Clear all codes
Take the vehicle for a test drive, preferably under similar operation conditions as the freeze frame data
Perform a visual inspection of the EVAP system looking for any broken or cracked components and lines
Test the gas cap with a cap tester
Using a scan tool the EVAP systems self test will be performed
A smoke machine will be used to check for and EVAP leaks
Lastly, the ECM will be tested if nothing else gives a conclusive answer
Common mistakes when diagnosing the P2401 code
The P2401 can be a tricky code to diagnose as there are many different components that can cause it.
Usually the gas cap is replaced and the code cleared. This may solve some cases of the P2401 but not all. In the cases where the code reappears, step by step diagnostic testing will be required to accurately diagnose this code.
How serious is the P2401 code?
The P2401 will not exhibit any concerns that prevent the vehicle from driving or running normally. It will however prevent the vehicle from passing emissions testing and may release fuel vapors into the atmosphere.
What repairs can fix the P2401 code?
- Gas cap is tested and replaced
- Charcoal canister replaced
- Leaking or cracked fuel vapor lines replaced
- Repairing or replacing the wiring harness
- ECM replaced as needed
- Faulty purge control solenoid replaced
- Leak detection pump replaced
Additional comments for consideration regarding the P2401 code
When the EVAP system has leaks they are usually vapor leaks. These leaks are usually to small to view unaided and may only be noticed either from the Check Engine Light or a fuel smell. When these occur a smoke machine is used to fill the EVAP system with a specific kind of smoke that will make the leaks appear so they can be repaired.
Need help with a P2401 code?
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