- Vehicles
- Cars
Charge port error detected
Tesla Charge port error detected: EV AC pilot signal fault
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
High
Quick answer
Alert CP_a151 ('Charge port error detected - Service is required') on a Tesla warns that the charge port cannot establish a valid control pilot signal with some AC chargers and non-Tesla DC Fast Chargers. Supercharging remains available while you schedule service.
Safety first
Stop and check this first
- Do not rely on AC charging without testing it first: even if you have a Gen 2 Mobile Connector or Gen 3 Wall Connector, Tesla recommends that you test and confirm the charge port communicates and charges as expected before relying on it.
- While CP_a151 is present, DC Fast Charging at non-Tesla stations may be limited or unavailable; use the touchscreen map to plan stops at Tesla Supercharger locations.
Safe checks you can perform
- Use the touchscreen map to locate a Tesla Supercharger for charging
- Test and confirm AC charging with a Gen 2 Mobile Connector or Gen 3 Wall Connector
- Schedule a service appointment at your earliest convenient opportunity
Leave these tasks to a qualified professional
- Do not attempt this professional task: Inspection and repair of the vehicle charge port control pilot circuit
- Do not attempt this professional task: Verification of standard AC charging and third-party DC Fast Charging compatibility
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Inspection and repair of the vehicle charge port control pilot circuit
What they doTesla Service inspects the vehicle charge port assembly and control pilot electronics to resolve the inability to establish a valid control pilot signal.
They must show youthe diagnostic test result identifying the fault in the charge port control pilot path.
In writingthe root cause of alert CP_a151, the charge port parts repaired or replaced, and pilot signal test results.
Verification of standard AC charging and third-party DC Fast Charging compatibility
What they doAfter servicing the port, the technician verifies that the vehicle establishes a valid control pilot signal on standard AC equipment as well as DC Fast Charging.
They must show youan active AC charging session on the touchscreen with alert CP_a151 cleared.
In writingconfirmation that control pilot communication is restored and CP_a151 no longer appears.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Use the touchscreen map to locate a Tesla Supercharger for charging
- Who:
- you, using the in-car navigation map when you need to charge.
- How:
- search the touchscreen map for Tesla Supercharger locations rather than relying on non-Tesla DC Fast Charging stations or public AC posts.
- Result that matters:
- keep the vehicle charged using Tesla Superchargers, which should continue to be available while CP_a151 is active.
- If the vehicle Supercharges normally:
- continue using Tesla Superchargers until your scheduled service visit.
- If Supercharging also fails or new alerts appear:
- contact Tesla Service promptly for assistance.
- Evidence to keep:
- photo of the touchscreen showing CP_a151 with 'OK to Supercharge' and the active Supercharging session.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts
Test and confirm AC charging with a Gen 2 Mobile Connector or Gen 3 Wall Connector
- Who:
- you, at your home charger before relying on an overnight AC charge.
- How:
- plug in your Gen 2 Mobile Connector or Gen 3 Wall Connector and verify on the touchscreen that the vehicle charge port communicates and charges as expected.
- Result that matters:
- confirm whether your specific Gen 2 Mobile Connector or Gen 3 Wall Connector still works in AC despite alert CP_a151.
- If your Gen 2 Mobile Connector or Gen 3 Wall Connector charges as expected:
- you can use that verified unit until your service appointment.
- If AC charging does not start or drops out:
- rely on Tesla Superchargers until the charge port is inspected.
- Evidence to keep:
- photo of the charging screen showing whether AC charging succeeded on the Gen 2 or Gen 3 unit.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts
Schedule a service appointment at your earliest convenient opportunity
- Who:
- you, booking an appointment through the Tesla Mobile App.
- How:
- open the Service section in the Tesla Mobile App, report alert CP_a151 ('Charge port error detected - Service is required'), and schedule an inspection of the vehicle charge port.
- Result that matters:
- arrange the required technician inspection to restore full AC and third-party DC Fast Charging capability.
- If your appointment is booked and you have Supercharger or verified Gen 2 / Gen 3 access:
- continue driving normally until the visit.
- If you have no Supercharger or working Gen 2 / Gen 3 charger nearby:
- note this in your service request so Tesla can prioritize support.
- Evidence to keep:
- screenshot of the Tesla Mobile App service booking referencing CP_a151.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Vehicles
- Brand
- Tesla
- Product type
- Cars
Known code variants
- AC charging may not function / OK to Supercharge
- Charge port error detected
- Charge port error detected - Service is required
- CP_a151
- Error del puerto de carga detectado
- Error del puerto de carga detectado - Se requiere servicio
- La carga de CA puede no funcionar/Se puede usar la supercarga
What it means
In the Tesla owner's manual, code CP_a151 displays 'Charge port error detected - Service is required' with 'AC charging may not function / OK to Supercharge'. It means the vehicle charge port is unable to establish a valid control pilot signal and communicate effectively with some AC charging equipment, so AC charging and non-Tesla DC Fast Charging may be limited or unavailable. Tesla Supercharging should remain available, and AC charging may still work with a tested Gen 2 Mobile Connector or Gen 3 Wall Connector. The alert alone never proves which internal part failed without service diagnosis.
Warnings and stop conditions
- Highsource verified
Do not rely on AC charging without testing it first: even if you have a Gen 2 Mobile Connector or Gen 3 Wall Connector, Tesla recommends that you test and confirm the charge port communicates and charges as expected before relying on it.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts
- Mediumsource verified
While CP_a151 is present, DC Fast Charging at non-Tesla stations may be limited or unavailable; use the touchscreen map to plan stops at Tesla Supercharger locations.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts
Symptoms and causes
Probable causes · in order
- Charge port unable to establish a valid control pilot signalCommon
The Tesla manual states that CP_a151 occurs when the vehicle charge port cannot establish a valid control pilot signal and communicate effectively with some AC charging equipment and power sources.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts
- Loss of handshake with standard AC stations and non-Tesla DC Fast ChargersPossible
While CP_a151 is present, standard AC charging equipment and third-party DC Fast Charging stations may be limited or completely unavailable.
Evidence: Tesla Model 3 owner manual: troubleshooting alerts
Virtual technician
Does Charge port error detected still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
Was this entry useful?