B1564 — Door Ajar Circuit Open

B1564 — Door Ajar Circuit Open. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: damaged wiring in door jambs or wet areas, faulty switch, motor or actuator of the affected system, blown fuse or failed relay.

body electrical

Is it safe to drive?

Short-term driving is OK Usually safe to drive — body codes rarely affect drivability. Exceptions: exterior lighting and wipers in bad weather, and central locking faults that can leave the car unsecured.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm B1564 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 body electrical system for damage, corrosion, chafing or poor contact.
Subsystem check Do a continuity test end-to-end on the door ajar circuit and wiggle the harness while measuring — intermittent opens show up as fluctuating readings.
Subsystem check Operate the affected function while watching its switch and motor PIDs in live data.
Subsystem check Inspect connectors and wiring at flex points (door jambs, tailgate hinges) — wires break there first.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm B1564 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for B1564 (parts and labor, USD, independent shop rates): Repair wiring or connectors: $80–$250; Replace the switch or actuator: $120–$450; BCM repair or replacement: $300–$900. Overall, fixing B1564 usually costs between $80 and $900. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What does OBD2 code B1564 mean?

What are the symptoms of B1564?

Drivers most often notice: warning light on the dashboard, no impact on engine operation in most cases, the affected function (locks, windows, lighting, wipers) works intermittently or not at all.

How much does it cost to fix B1564?

Repair wiring or connectors — $80–$250; Replace the switch or actuator — $120–$450; BCM repair or replacement — $300–$900. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

Is it safe to drive with B1564?

Usually safe to drive — body codes rarely affect drivability. Exceptions: exterior lighting and wipers in bad weather, and central locking faults that can leave the car unsecured.

What is the most common cause of B1564?

The most common causes are: damaged wiring in door jambs or wet areas, faulty switch, motor or actuator of the affected system, blown fuse or failed relay.

When your scan tool pulls code B1564, it's telling you the body control module has detected a problem with the door ajar circuit. The term "circuit open" indicates the electrical pathway that the module expects to find intact has been interrupted somewhere. No current is flowing where it should be, and the module logs this condition when it persists long enough to cross the diagnostic threshold.

The door ajar circuit is part of your vehicle's body electrical system. It monitors whether doors are open or closed and feeds that information to the BCM, which uses it for interior lighting, security features, and dashboard indicators. When the circuit opens—whether due to a broken wire, a bad connection, or a failed component—the BCM can't get a valid signal. After a set number of drive cycles, it stores B1564 and illuminates the check engine or body indicator light. The freeze frame data captured alongside the code shows engine speed, load, temperature, and vehicle speed at the exact moment the fault occurred, giving you a snapshot of driving conditions when the problem appeared.

Common Symptoms

Dashboard warning light stays on after the engine starts
Interior lights may fail to turn on or off automatically when doors open and close
The door-open indicator on the instrument cluster may display incorrectly or erratically
Central locking may behave unpredictably or not respond to door position
No effect on engine performance or drivability in most vehicles
Affected accessories like map lights, cargo lights, or step-well lighting may stop working
Intermittent operation where the problem comes and goes with vibration or weather changes

Typical Causes

Broken or frayed wire in the door ajar wiring harness, especially near hinges and door jambs
Blown fuse protecting the door ajar circuit or related body electrical circuit
Loose, corroded, or unplugged electrical connector at the door harness or BCM
Backed-out terminal pin in a connector causing intermittent contact
Failed door ajar switch or plunger-style sensor internally open
Water intrusion or moisture corrosion in connectors located in wet areas
Faulty door latch assembly with integrated ajar switch
Body control module itself failing to process the signal correctly

How to Diagnose

Connect your OBD2 scanner and verify B1564 is currently stored. Record the freeze frame data—this tells you engine RPM, load, and vehicle speed when the fault first appeared and helps you recreate those conditions during testing.
Look for any related diagnostic trouble codes. Body electrical problems often come in pairs; a secondary code may point you directly to the failing component rather than the circuit itself.
Perform a thorough visual inspection of the door ajar wiring and connectors. Focus on the flexible sections near door hinges and any connectors exposed to the elements. Look for cracked insulation, green corrosion buildup, and wires that pull free easily.
Use a multimeter to check continuity along the entire door ajar circuit from the BCM to the switch. While measuring, gently wiggle the harness and connectors—an intermittent open will show up as fluctuating resistance or an open circuit when the wire moves.
Monitor live data from the door ajar switch while manually opening and closing each door. Compare the PID values against what you know is actually happening. A switch that shows "closed" when the door stands open tells you exactly where to dig deeper.
After repairs are complete, clear the code and drive the vehicle through a complete drive cycle, including conditions similar to those captured in the freeze frame. Verify the light stays off and the fault does not return.

Repair Options and Costs

Wiring and connector issues are the most frequent culprits. Sourcing the damaged section, soldering or splicing connections, and sealing against moisture typically runs between $80 and $250 depending on accessibility and labor time.

If the door ajar switch itself has failed—common in older vehicles with plunger-style sensors—replacement of the switch or entire door latch assembly generally costs $120 to $450, with parts prices varying by make and model.

When the body control module is at fault, repair or replacement is more involved. BCM repair through a specialist or full module replacement with programming typically falls between $300 and $900 including parts and labor.

Total Cost to Fix B1564

Expect to spend anywhere from $80 for a simple wiring repair up to $900 for BCM replacement. The majority of cases resolve in the lower-to-mid range once the actual cause is identified. Skipping a proper diagnosis and jumping to expensive parts replacement is the fastest way to overspend on this code.

Can You Drive With B1564?

Yes—in most cases, B1564 poses no immediate threat to drivability. Engine power, transmission function, and braking remain unaffected. The practical concern is that you may be operating without proper door ajar feedback: exterior lighting may not function correctly in low visibility, wipers could behave unexpectedly if linked to the circuit, and central locking faults might leave your vehicle unsecured. Use reasonable caution and address the underlying issue at your earliest convenience.