Direct answer: P0513 on a Subaru means “Incorrect Immobilizer Key – the key presented was not recognised by the immobilizer system.” In practice this usually means the vehicle’s key transponder and the immobilizer module are out of sync — the correct fix is to confirm which key is at fault and then reprogram or replace the key or immobilizer using proper key‑programming equipment.

Key Takeaways

• P0513 = Incorrect Immobilizer Key (key not recognised by immobilizer).
• Common causes: bad/wrong key transponder, dead key battery (push‑start), failed immobilizer antenna, or a programming mismatch.
• Diagnosis order: scan, try spare key, check key battery and antenna, inspect wiring/connectors, then reprogram or replace as needed.
• Correct fixes are key reprogramming or module programming/replacement — an automotive locksmith or module programmer is the right specialist.
• If the car won’t start or restarts intermittently, don’t ignore it — call a pro to avoid being stranded.

What P0513 Means in Plain English

The factory definition for Subaru P0513 is: “Incorrect Immobilizer Key – the key presented was not recognised by the immobilizer system.” That means when the vehicle received the transponder code from the key, the immobilizer system did not find a matching authorized code in its memory and flagged the event. Modern immobilizer systems compare a key’s transponder ID against stored IDs before allowing the engine to start.

How Subaru Immobilizer Systems Work (brief)

• The key contains a passive transponder chip with a unique ID.
• The immobilizer antenna (around the ignition cylinder or push‑button area) reads that ID when the key is presented.
• The immobilizer control unit or body module checks the read ID against stored authorized keys.
• If the ID isn’t known, the immobilizer prevents the engine from starting and logs P0513.

Common Causes of P0513 on Subaru

• Damaged or incorrect key transponder (after replacing a key or receiving the wrong aftermarket key).
• Key fob battery dead (for push‑button start systems the transponder needs power to talk to the antenna).
• Faulty immobilizer antenna or poor connection to the antenna coil.
• Wiring or connector issues between the antenna, immobilizer module and BCM.
• Software mismatch after module replacement or a failed immobilizer/module memory corruption.

Symptoms Drivers Notice

• Engine won’t crank or starter is disabled even though the car tries to accept the key.
• Car cranks but cuts out immediately or won’t keep running.
• Key works intermittently — one key works, the other does not.
• Security/immobilizer warning light on the dash.
• Door locks, remote functions, or push‑start behaviour are inconsistent.

Quick Reference: Causes, Symptoms, and First Actions

Likely Cause	Most Common Symptom	Immediate DIY Check
Bad/uncoded key	Key not recognised / won’t start	Try spare key; if spare works, key is the issue
Dead key fob battery (push‑start)	No response from push button / intermittent start	Replace fob battery; hold key near start button and try
Faulty antenna or wiring	Multiple keys fail; immobilizer light on	Inspect antenna connector under the dash for loose pins
Module/programming mismatch	Fault after module swap or ECU work	Confirm recent work; ask tech to check programming

How a Technician Diagnoses P0513: Tools and Step-by-Step

Diagnosis should be methodical. A competent tech uses the right scan tool first, then isolates the key, antenna, and module in that order.

Tools you’ll see used

• OBD‑II scanner with Subaru/immobilizer capability (OEM-level or a capable aftermarket scanner).
• Manufacturer-level key‑programming tool or an automotive locksmith’s programmer.
• Multimeter for basic continuity and voltage checks on antenna wiring.
• Small scope (optional) to inspect transponder antenna waveform if needed.

Step-by-step diagnosis (real order)

1. Connect a scan tool at the OBD‑II port and read codes and freeze frames. Confirm the code P0513 and note any related SRS, BCM, or immobilizer codes.
2. Try a known-good spare key. If the spare is recognised, the problem is the key transponder or key programming — not the car module.
3. Check the key fob battery (for push‑start): swap or measure the voltage. A dead battery can prevent the transponder from responding.
4. Visually inspect the immobilizer antenna/coil area (around the ignition cylinder or push‑button bezel) for damage and check the connector under the dash. Wiggle tests can reveal intermittent pins.
5. Use a multimeter to verify power and ground at the antenna and trace connector continuity back to the immobilizer/BCM.
6. If wiring and antenna are good, attempt key reprogramming with an OEM-level programmer. Reprogram both the vehicle and the key so their IDs match.
7. If reprogramming fails, perform module-level checks: confirm immobilizer module communicates with the scan tool. If the module is faulty or has corrupted memory it may need replacement and programming.

Fixes: What Actually Repairs P0513

There are only a few correct fixes — you either reprogram the key, replace the key (and program the new one), or reprogram/replace the immobilizer/module that stores the authorized key IDs. Which one is appropriate depends on the diagnosis:

• Key is at fault → key programming (automotive locksmith can cut and program a new key).
• Antenna or wiring fault → repair the wiring or replace the antenna (done by a technician; wiring fault must be fixed to allow programming to work reliably).
• Module mismatch or failure → module programming or module replacement and programming with dealer or module-programming service.

When It’s Safe to Drive

If P0513 leaves the engine running normally and no warning lights remain, the car may be drivable short‑term. However, if the code is causing intermittent stalling, failure to start, or immobilizer light warnings, do not rely on the vehicle for long trips — you risk being unable to restart the car. Get the car diagnosed and have keys reprogrammed or the module diagnosed promptly.

How LockNCal Helps

For key and immobilizer faults like P0513 we recommend an automotive locksmith or module programmer. LockNCal offers on‑site key services and module programming — a technician can come to your location to cut and program keys or perform module programming as needed. See our car key copy services for key reprogramming and our module programming page for module-level work.

Relevant services: mobile car key copy & programming, module programming, and you can schedule an appointment online or call (469) 277-7277.

Practical Tips Before You Call

• Try every mechanical and remote key you own — if a spare works the fix is usually inexpensive.
• Replace the key fob battery before anything else on push‑start models.
• Note any recent work to the vehicle (battery disconnects, module swaps) — that history helps the technician zero in on programming mismatches.
• Have your VIN and proof of ownership ready for key programming or module work.

FAQ

Soft CTA: If your Subaru is showing P0513 and you need key programming, locksmith service, or module programming, we can help — schedule an appointment online at https://lockncal.com/schedule-your-service-appointment/ or call (469) 277-7277 to speak with a technician.

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