B1600 on 1997-2004 Ford F-150 (XL, XLT, Lariat, FX4, King Ranch) — PATS Ignition Key Transponder Signal Is Not Received
1 vehicles · 1 makes · $100-$500 repair
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Ford F-150 · 1997–2004
The Passive Anti-Theft System (PATS) on these trucks disables fuel/injection when the PCM cannot verify the key transponder, leaving the truck cranking but not starting with the dash theft/security light flashing rapidly. Common triggers are a worn or dead key transponder, a loose or damaged transceiver antenna ring around the ignition cylinder, corroded PCM grounds (water intrusion at the passenger cowl/windshield), or intermittent PCM power. It often starts as an intermittent no-start that worsens.
Common Symptoms
- Engine cranks but will not start
- Theft/security light flashes rapidly or stays on
- Intermittent no-start that comes and goes
- Starts with one key but not another
- Dies immediately after starting
How to Fix
Read PATS/PCM DTCs. Try a known-good second key; re-seat/replace the ignition antenna ring; clean and tighten PCM/body grounds and check for windshield/cowl water leaks; verify PCM power and keep-alive. Re-program keys or replace the PATS/PCM as a last resort. Keeping two working programmed keys avoids most stranding.
Sources for this issue (1)
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B1600 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does B1600 mean?
B1600 stands for "PATS Ignition Key Transponder Signal Is Not Received." A Ford (also Lincoln/Mercury and some Mazda) body code for the PATS passive anti-theft system. The PATS module received no transponder signal at all from the ignition key during the start sequence — either the key has no working chip, or the antenna/transceiver ring around the ignition lock cylinder never picked it up. PATS disables fuel and spark (not the starter), so the engine cranks normally but will not start or will start and immediately stall, and the theft/security light stays on or flashes rapidly.
What are the most common causes of B1600?
The most common causes of B1600 are: Damaged or dead transponder chip inside the key (the single most common cause), Using a non-transponder, aftermarket, or unprogrammed key, or a physically damaged key head, Faulty or unplugged transceiver antenna ring at the ignition lock cylinder, Damaged wiring or a poor connection between the antenna ring and the PATS module/instrument cluster, Interference from a second transponder key or metal object on the same keyring, Failed PATS module / instrument cluster. The specific cause varies by vehicle.
How much does it cost to fix B1600?
Repair costs for B1600 range from $100 to $500, depending on the vehicle and root cause.
Which vehicles are affected by B1600?
Au7o has documented B1600 across 1 vehicle models from 1 manufacturers: Ford.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.