B1600 – PATS Ignition Key Transponder Signal Is Not Received

By Reinier (Contact Me)
Last Updated 2019-06-20
Automobile Repair Shop Owner

Trouble CodeFault LocationProbable Cause
B1600 PATS Ignition Key Transponder Signal Is Not Received

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What Does Code B1600 Mean?

OBD II fault code B1600 is a manufacturer specific code that is defined by car maker Ford as “PATS Ignition Key Transponder Signal Is Not Received”, or sometimes as “No PATS Key Read by the PATS Control”, and is set when the PCM (Powertrain Control Module) detects a communication failure between a PATS key and the PCM/Immobilizer. Note that the word “PATS” refers to the Passive Anti-theft System on Ford products.

NOTE: Code B1600 is also used by General Motors, who defines it as “LF (Left Front) mirror motor #1 (single motor or vertical) circuit malfunction”

On Ford applications, the operation of the PATS system depends on the PCM being able to read the security code that is encrypted into a compatible PATS ignition key. Note that unlike similar systems on other vehicle brands, the encryption on Ford PATS key is stored on a chip within the key that does not require a power source to function.

In terms of operating principles, when a PATS key is inserted into the ignition switch and turned to either the “ON” or “START” position, the PCM sends a signal to the PATS transceiver, which initiates a process of communication with the key . This process establishes a link with the transponder in the key in order to read the encrypted security code that is stored in the key; the retrieved code is then sent to the PCM, which then compares the obtained code with the codes that is stored in a dedicated part of its memory.

If the code that was retrieved from the key matches one of the codes stored in the PCM, it will ground the starter motor solenoid and enable the fuel injectors, thus enabling the engine to start. If however, the retrieved code does not match one of the codes stored in the PCM, the PCM will not ground the starter motor solenoid and enable the fuel injectors, thereby effectively preventing the engine from starting.

However, even if the retrieved security code does match a code stored in the PCM, but the PCM detects a failure, malfunction, defect, or abnormal voltage anywhere in the PATS system, the PCM will not ground the starter motor or enable the fuel injectors. Since the PCM cannot always distinguish between genuine failures or defects and attempts to tamper with the PATS system, keeping the starter motor and fuel injectors disabled is a default reaction when one or more parts of the PATS system does not work as expected.

Nonetheless, when the PCM detects either a PATS key code that does not match a stored code, or any defect, failure, malfunction or abnormal voltage anywhere in the PATS system it will disable both the starter motor and the fuel injectors, in addition to setting one or more trouble codes and illuminating a warning light.

Where is the B1600 sensor located?

The image above shows a typical Ford PATS key, with the chip (circled) on which the particular vehicle’s PATS security code is encrypted.

What are the common causes of code B1600?

The most common causes of code B1600 could include one or more of the following-

  • Damaged or defective PATS key
  • Incorrectly programmed PATS key
  • Non-programmed PATS key
  • Fewer than two PATS key codes are programmed into the PCM
  • Damaged, burnt, shorted, disconnected, and/or corroded wiring/connectors anywhere in the PATS system
  • Damaged or defective PATS transceiver
  • Damaged or defective PCM, but note that since this is a rare event, the fault must be sought elsewhere before any control module is replaced

What are the symptoms of code B1600?

The symptoms of code B1600 are the same across all Ford applications, and typically include the following-

  • Stored trouble code and illuminated warning light
  • One or more additional security/anti-theft related codes may be present along with B1600
  • The anti-theft warning light may be illuminated permanently, or may not illuminate at all
  • Engine will not crank

BAT Team Discussions for B1600

  • 98 ford explorer 2.0
    98 ford explorer 4. 0 4x2 it won`t start code B1600 I did replased the transponder sensor and still get same code is any one know how to reset the an ta theft system on these truck or what could be wrong...
  • 98 ford explorer 4.0
    code B1600 truck won`t start anti thift light flashing how can I fix that any one know...