NATS Lock Mode Detected

What it means

This is a Nissan-specific code for vehicles with the NATS anti-theft system; the same number can mean something different on other makes. It means the engine computer (ECM) has entered lock mode after repeated start attempts in which the key was not recognized, or after a communication fault with the immobilizer unit. In lock mode the engine will not start, even with the correct key, until the lock is released.

Models covered: Nissan (and Infiniti) models with NATS (Nissan Anti-Theft System), mainly around 1999–2008 (e.g. Altima, Maxima, Sentra, Pathfinder, X-Trail).

Related codes: P1611P1612P1614P1615

Symptoms4

• The engine cranks but does not start, or does not respond at all.
• The security indicator light in the cluster stays on steadily with the ignition on.
• The fault appeared after repeated start attempts with a spare or copied key.
• Another NATS code that points to the root cause may be stored alongside it.

Possible causes6

• Repeated start attempts with a key that is not registered, such as a copied key without a correct chip.
• A weak or damaged transponder chip inside the key.
• Interference from other keys or metal objects on the same key ring.
• A fault in the NATS antenna around the ignition key cylinder or its wiring.
• Lost communication between the immobilizer unit (IMMU) and the ECM due to a wire or connector.
• An ECM or immobilizer unit replaced without the required registration.

How to diagnose5

1. Read all stored codes; P1610 is usually accompanied by another code such as P1614 or P1615 that names the root cause.
2. Try starting with the original key alone, away from other keys and metal objects.
3. Try the original spare key if available; if the engine starts with it, the first key is the likely problem.
4. Inspect the NATS antenna connector at the key cylinder and the immobilizer unit connections.
5. Use a Nissan-capable scan tool to read NATS status and release lock mode per the service manual.

How to fix6

1. Remove other keys and metal objects from the ignition key and try again.
2. Perform the lock mode release procedure in the service manual, which cycles the ignition with a registered key, or release it with a Nissan-capable scan tool.
3. Repair any damaged wire or connector in the antenna or immobilizer circuit.
4. Have the keys registered again at a dealer or a specialist with Nissan programming equipment if the key is not registered.
5. Replace a faulty key or NATS antenna once confirmed, then register the keys.
6. Clear the codes, then start the engine several times and confirm the code does not return.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low when releasing lock mode or removing other keys is enough, and rises when a new key with programming or a new antenna is needed, since programming requires Nissan-specific equipment.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions