My car cranks but won't start with B1600 — what should I try first?

Try a spare key. If the car starts with the spare, the original key's transponder chip has failed and that key needs to be replaced or re-chipped. Before anything else, also strip the key ring down to just the one key — a second transponder key or a fuel-payment fob touching the ignition can block the antenna from reading your key at all, and that costs nothing to rule out.

How is B1600 different from B1601, B1602, and B1213?

They're a family, and the distinction tells you exactly where to look. B1600 means NO key was read — the antenna energized and heard nothing, so suspect the chip, antenna ring, wiring, or module. B1601 means a key WAS read but it isn't programmed to this vehicle (a valid but unrecognized key — it just needs programming). B1602 means only a PARTIAL code came back, which usually means interference or a marginal chip. B1213 means the system has fewer than two keys programmed. And a true antenna failure often shows up as B2103. If you only have B1600, don't start with programming — start with the key, antenna, and wiring.

Does any transponder key work, or does it have to be a specific type?

It has to be a compatible PATS key. Ford lists approved brands — Ford/Motorcraft, Strattec, ILCO, Rotunda, HUF, and Valeo — and using an off-brand or wrong-family chip is a common reason a freshly cut key reads intermittently or throws B1600/B1602. Match the correct transponder family for your year and model. A good automotive locksmith will know which chip your PATS system expects, which is why cheap online keys so often disappoint.

Can a locksmith clone my working key instead of programming a new one?

Often, yes, and it can be the cheaper, faster path. If you already have one key the car accepts, many Ford PATS transponders can be cloned onto a new chip that the vehicle sees as identical to the original — no security relearn or scan tool required, so the car doesn't even need to know a new key exists. Cloning won't help if you have no working key or need to erase lost keys; in that case you need true programming and the security relearn.

Can I program a new PATS key myself?

Sometimes. Many Ford models support a two-key on-board procedure: if you already have TWO keys the car accepts, you can add a third by cycling the ignition through both within a set time — no tools needed. But adding a key when you only have one, or erasing lost keys, requires a scan tool (or software like FORScan) and a security-access wait, commonly about 10 minutes, before the module will let you rewrite key data. If the DIY procedure doesn't apply to your vehicle, an independent locksmith or dealer can cut and program the key.

Is B1600 a sign someone tried to steal my car?

Usually not. PATS logs B1600 any time it can't verify a key, and by far the most common trigger is an ordinary fault — a failing chip, a loose antenna ring, or key-ring interference — not a break-in. A theft attempt with a wrong key would more typically read as an unprogrammed key (B1601). If the car starts fine with your own key and the code doesn't return, it was almost certainly a read fault, not a thief.

OBD-II trouble code

B1600: PATS Ignition Key Transponder Signal Is Not Received

Ford's Passive Anti-Theft System did not receive a valid signal from the ignition key's transponder chip. The engine may crank but not start because the anti-theft system has disabled it.

Quick facts

System: Body
Category: Anti-Theft / Immobilizer
Severity: Medium severity
Drivable: No — stop driving until repaired
Repair cost range: $60 – $500
DIY difficulty: Intermediate DIY

What does B1600 mean?

B1600 is a manufacturer-specific Ford body (B) code: 'PATS Ignition Key Transponder Signal Is Not Received.' PATS stands for Passive Anti-Theft System — Ford's immobilizer. Every PATS key contains a small glass transponder chip with no battery of its own. When you turn the key on, a transceiver antenna ring around the ignition lock cylinder emits a low-frequency field that energizes that chip; the chip answers back with its unique code, the transceiver relays it to the PCM (or the PATS/immobilizer module), and only if the code matches a stored key does the PCM enable fuel and spark and allow the engine to run.

The precise meaning of B1600 matters: it is set when the system receives NO transponder signal at all — the antenna energized but nothing answered. That is different from its close siblings, and telling them apart saves a lot of wasted money. B1601 means a key WAS read but it isn't programmed into this vehicle's memory (a valid but unrecognized key). B1602 means only a PARTIAL key code was read, which typically points to interference or a marginal chip. B1213 means fewer than two keys are programmed. B2103 is a transceiver (antenna) module failure. So B1600 specifically says 'I energized the coil and heard nothing back' — pointing at the chip itself, the antenna ring, the wiring between the antenna and the PCM, or the module, rather than at a programming or matching problem.

Because PATS immobilizes the engine as a fail-safe, the practical effect is a no-start: the engine usually cranks normally but won't start, or fires for a moment and stalls, typically with a flashing theft/security indicator. This is not a mechanical engine fault — it is the anti-theft system withholding start permission because it could not verify a key.

Common causes

Failed or cracked transponder chip inside the key (the glass chip can fracture if the key is dropped or abused)
Low-quality or wrong-type aftermarket key whose chip the system can't read
Faulty or dislodged transceiver antenna ring around the ignition lock cylinder (often coded separately as B2103 when the antenna itself fails)
Wiring or connector fault between the antenna ring and the PATS/PCM module
Heavy interference at the ignition — a second transponder key, a fuel-purchase transponder (e.g. Speedpass), or large metal objects on the ring (more often produces a partial-read B1602, but can degrade reads)
Failed PATS/immobilizer control module or PCM
Discharged coin-cell battery in a push-button/smart-key system (on keyless applications)

Symptoms

Engine cranks normally but will not start, or fires briefly and stalls
Flashing theft/security indicator in the instrument cluster
Vehicle in anti-theft (immobilizer) mode
Intermittent no-start tied to one specific key, or that clears when other keys are taken off the ring

Diagnostic steps

1.Try a known-good spare key. If the vehicle starts with the spare, the original key's transponder is the likely fault — this single test separates a key problem from a vehicle-side problem faster than anything else.
2.Take every other transponder key, fuel-payment fob, and heavy metal object off the ring so only the working key is near the lock, then retry — chip-to-chip interference is a common, free fix.
3.Confirm the key is an approved PATS type (Ford/Motorcraft, Strattec, ILCO, Rotunda, HUF, or Valeo). A cheap or wrong-family aftermarket chip may read intermittently or not at all.
4.Scan the PATS/immobilizer system and note the exact code(s): B1600 (no read) points at chip/antenna/wiring/module, while B1601 (unprogrammed), B1602 (partial read), or B1213 (fewer than 2 keys) point elsewhere.
5.Inspect the transceiver antenna ring around the ignition cylinder for proper seating, cracks, or a disconnected/corroded connector; a confirmed antenna failure usually sets B2103.
6.Check the wiring and connector between the antenna ring and the module for breaks, chafing, or corrosion.
7.If key, antenna, and wiring check out, test the module/PCM per the service procedure.
8.Cut and program (or clone) an approved key as required, then confirm the engine starts and the theft light goes from flashing to a brief solid-then-off arm cycle.

Repair cost

$60 – $500

A replacement transponder key cut and programmed typically runs $60-$250 depending on whether it's a basic bladed key or a smart/proximity fob. If you already have one working key, a locksmith can often CLONE it onto a new chip for less than dealer programming, since cloning skips the security relearn. Antenna-ring or wiring repairs are usually modest; a failed module or PCM with programming sits at the high end. Smart-key and dealer-only applications push costs up — an independent automotive locksmith is frequently the cheaper route for cutting and programming.

Estimate your repair

Run the numbers for your vehicle

Open the Repair Cost Estimator with immobilizer key / anti-theft service preselected. Adjust labor rate and vehicle category to fit your situation.

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DIY vs shop

This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.

Related codes

B1601 B1602 B1213 B2103 P0513