B1600 — PATS Ignition Key Transponder Signal Is Not Received

B1600 — PATS Ignition Key Transponder Signal Is Not Received. A fault in the ignition system. Short, gentle driving to a shop is usually possible. Typical causes: damaged coil wiring or connector, moisture or oil in the spark plug wells, faulty ignition control circuit in the ECM.

body electrical

Is it safe to drive?

Drive with caution Drive with caution and avoid load. Ignition faults cause misfires that quickly overheat and destroy the catalytic converter; if the Check Engine Light flashes, stop and fix it first.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm B1600 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many B0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the ignition system for damage, corrosion, chafing or poor contact.
Subsystem check Swap the coil to another cylinder and see if the fault code follows it.
Subsystem check Inspect spark plugs for wear, oil or carbon tracks and check plug gaps.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm B1600 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for B1600 (parts and labor, USD, independent shop rates): Replace spark plugs: $90–$250; Repair coil wiring or connector: $80–$250; Replace an ignition coil: $150–$380. Overall, fixing B1600 usually costs between $80 and $380. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What is the most common cause of B1600?

The most common causes are: damaged coil wiring or connector, moisture or oil in the spark plug wells, faulty ignition control circuit in the ECM.

Is it safe to drive with B1600?

Drive with caution and avoid load. Ignition faults cause misfires that quickly overheat and destroy the catalytic converter; if the Check Engine Light flashes, stop and fix it first.

What are the symptoms of B1600?

Drivers most often notice: hard starting, especially in damp weather, misfires under load or at idle, loss of power and jerking, increased fuel consumption.

How do I diagnose B1600 myself?

Start with a scan: confirm B1600, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the ignition system, and verify the suspect component against live data before buying parts.

How much does it cost to fix B1600?

Replace spark plugs — $90–$250; Repair coil wiring or connector — $80–$250; Replace an ignition coil — $150–$380. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

When your vehicle's computer detects a problem with the ignition key transponder signal, it logs OBD2 code B1600. This fault belongs to the body electrical category and specifically indicates that the Passive Anti-Theft System (PATS) failed to receive a valid signal from the ignition key's transponder chip. In plain terms: the engine control module queried the key, and nothing came back.

The affected system relies on a small radio-frequency transponder embedded in your ignition key. When you turn the key, the PATS control module sends a challenge signal to the transponder. If the chip responds with the correct identification code, the engine is allowed to start. When that handshake never happens or the signal never arrives, the control module records B1600 and may prevent the engine from running entirely. The ECU typically requires the fault to appear across multiple drive cycles before storing the code, which means a single glitch probably won't trigger it — persistent conditions do.

Beyond storing the diagnostic trouble code, the module captures a freeze frame snapshot at the moment of failure. That snapshot records engine RPM, load percentage, coolant temperature, and vehicle speed. Reviewing those values before diving into component testing tells you exactly what conditions caused the fault and cuts down guesswork significantly.

Symptoms of B1600

Engine cranks but refuses to start, particularly when humidity is high or moisture is present
Misfires occurring under load or even while idling
Noticeable loss of engine power and irregular acceleration
Fuel economy drops noticeably compared to normal
Check Engine Light or security warning lamp illuminates on the dashboard

Causes of B1600

Moisture or engine oil contamination in the spark plug tube wells, disrupting the secondary ignition circuit
Faulty ignition control circuit within the engine control module itself
Damaged wiring harness or corroded connectors feeding the ignition coil circuit
Complete failure of the ignition coil or coil pack assembly
Damaged or depleted transponder chip inside the ignition key
Poor electrical ground connections related to the ignition system
Faulty crankshaft position sensor sending incorrect engine position data

How to Diagnose B1600

Hook up an OBD2 scanner and retrieve all stored codes, paying special attention to the freeze frame data associated with B1600. Note the engine conditions recorded at the moment of failure — those details guide the rest of the procedure.
Scan for any additional trouble codes. Codes in the B0xxx family often share underlying causes, and related electrical faults can point you directly to the root problem. Also check for any manufacturer TSBs (Technical Service Bulletins) that apply to your specific make and model — many ignition-related faults have published factory solutions or software calibrations.
Perform a thorough visual inspection of the ignition system wiring harness. Look for chafed insulation, bent or pushed-out pins in connectors, corrosion buildup, and any signs of heat damage or rodent interference.
Test the ignition coil output by swapping it with a known-good coil from another cylinder. If the fault code moves to the new cylinder, you've confirmed a bad coil. If it stays put, the problem lies elsewhere in the circuit.
Remove and inspect the spark plugs. Check for oil fouling, carbon tracking on the ceramic insulator, eroded electrodes, and incorrect gap settings. Replace any plugs that show contamination or excessive wear.
Clear the codes after your inspections, then complete a full drive cycle that recreates the conditions captured in the freeze frame. Monitor whether B1600 reappears — a code that does not return after this test indicates the issue was transient.

Repair Options for B1600

Addressing the most common and least expensive possibilities first saves both time and money:

Spark plug replacement: Typically $90–$250 depending on plug type and labor
Ignition coil wiring or connector repair: Generally $80–$250 for parts and professional repair
Ignition coil or coil pack replacement: Usually $150–$380 depending on vehicle application and part sourcing

How Much Does It Cost to Fix B1600?

The final bill hinges entirely on which component is actually at fault. Using the price ranges above and assuming standard independent shop labor rates in USD, here is how typical scenarios shake out:

Spark plug replacement alone: $90–$250
Wiring or connector repair only: $80–$250
Ignition coil replacement in isolation: $150–$380

In most cases, resolving B1600 costs somewhere between $80 and $380 total. Ruling out cheaper fixes first is the smart approach — the priciest parts are rarely the culprit on the first pass. Spending $30 on a set of ignition wires or $15 on dielectric grease for a damp connector beats jumping straight to a $300 coil pack.

Can You Drive with B1600?

Use caution. Persistent ignition faults cause cylinder misfires, and unburned fuel entering the exhaust stream overheats the catalytic converter, potentially causing thousands of dollars in damage. If the Check Engine Light is flashing rather than steady, stop driving immediately and address the problem before continuing — flashing CEL indicates a misfire active enough to damage emissions equipment right now.