B1573 — Door Ajar LR Circuit Short To Battery

OBD2 code B1573 flags a problem with the body electrical system (door ajar LR circuit short to battery). The car is usually drivable while you plan the repair. Common culprits: corroded or loose connectors, body control module (BCM) fault, damaged wiring in door jambs or wet areas.

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 B1573 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 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 B1573 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for B1573 (parts and labor, USD, independent shop rates): BCM repair or replacement: $300–$900; Repair wiring or connectors: $80–$250; Replace the switch or actuator: $120–$450. Overall, fixing B1573 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

How much does it cost to fix B1573?

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

What are the symptoms of B1573?

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

What does OBD2 code B1573 mean?

What is the most common cause of B1573?

The most common causes are: corroded or loose connectors, body control module (BCM) fault, damaged wiring in door jambs or wet areas.

Will B1573 clear itself?

Sometimes B1573 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

When your scan tool pulls code B1573, the body control module has detected that the left-rear door ajar circuit is drawing battery voltage when it shouldn't be. This is classified as a body electrical fault, not an engine or drivetrain problem. The BCM constantly watches the door switch circuits while you drive, looking for specific voltage patterns that tell it whether each door is open or closed. When the signal from the left rear door stays at battery voltage instead of switching between open and closed states, the module logs B1573 and illuminates the check-engine or body-system warning light.

The BCM relies on these door ajar signals for more than just interior lighting. It uses them to control the security system, auto-lock features, and sometimes the chime that reminds you a door is open. Because these inputs feed into multiple functions, an inaccurate door-ajar reading can cause unpredictable behavior from locks, windows, or the alarm. The stored freeze frame data captures engine RPM, load, temperature, and vehicle speed at the exact moment the fault first appeared—information that helps you recreate the conditions during testing.

Symptoms of B1573

No effect on engine performance or fuel economy in most vehicles
Interior lights may stay on or fail to turn on when the left rear door opens
Central locking operates erratically or ignores the left rear door switch
Dashboard warning light stays illuminated until the fault is cleared
Window controls or other body functions that depend on door-ajar input behave intermittently
In some cases, the security system may arm or disarm unexpectedly due to false door-status data

Common Causes

Damaged wiring inside the door jamb is the most frequent culprit. The left rear door hinge area flexes every time you open and close it, and the wires inside the rubber boot eventually crack or break from repeated bending. Moisture accelerates this by causing corrosion at the connector pins, which creates high resistance and causes the BCM to misinterpret the signal. Loose or pushed-back connector terminals produce similar symptoms. Before assuming the BCM itself has failed, rule out the simple stuff—a blown fuse for the body control circuit or a faulty relay can also generate B1573. A failing body control module is possible but less common and more expensive to repair.

How to Diagnose B1573

Hook up your OBD2 scanner and confirm that B1573 is an active or stored code. Save the freeze frame data so you know the vehicle speed, engine load, and temperature when the fault occurred.
Look for any other body-related codes that appear alongside B1573. When multiple door-ajar codes set simultaneously, a single wiring problem or a BCM power supply issue is usually to blame. Check whether the manufacturer has published a TSB for your specific model—search by VIN on the manufacturer's website or nhtsa.gov.
Visually trace the left rear door wiring harness from the connector inside the cabin through the door jamb and into the door itself. Peel back the rubber boot and look for broken insulation, corroded pins, or wires that pull out of the connector.
Use your scanner's live data function to watch the door-ajar PID while someone operates the left rear door switch manually. The reading should toggle between open and closed states. If it stays stuck at one value, the switch or its wiring is the problem.
Wiggle the connector and harness while monitoring live data. If the PID drops in and out as you move the wires, you've found an intermittent connection—typically at a flex point near the hinge.
Clear the code and complete a full drive cycle that reproduces the conditions recorded in the freeze frame. If B1573 returns, the fault is still present and needs repair.

Repair Options and Costs

Wiring or connector repair — If you find broken wires or corroded pins, repair or replace the affected sections. Solder and heat-shrink any splices, or replace the entire harness segment if damage is extensive. Cost: $80–$250 for parts and professional labor.

Switch or actuator replacement — The door-ajar switch itself can fail internally or become contaminated with debris. Replacement is straightforward in most cases. Cost: $120–$450 depending on the switch design and labor time.

BCM repair or replacement — If diagnostics eliminate all wiring and switch issues, the body control module may need to be rebuilt or replaced. Cost: $300–$900 for a used or refurbished unit plus programming and installation.

Total Cost to Fix B1573

The actual repair cost hinges on what component is faulty. Most cases involve wiring damage in the door jamb, which is the least expensive to fix. Replacing a failed door switch falls in the middle range. BCM replacement is the priciest scenario but represents a small percentage of cases. Expect to pay between $80 and $900 total for parts and labor at an independent shop. Spending time on a thorough diagnosis before purchasing parts always pays off—the most expensive repair is almost never the first thing to try.

Can You Drive with B1573?

Yes, in most situations you can continue driving. Body electrical faults like B1573 typically do not affect engine operation, transmission shifting, or braking. However, some scenarios warrant attention. If your exterior lights or wipers are affected, operate them carefully in poor weather. A faulty door-ajar signal can also cause central locking to behave erratically, which may leave the vehicle unsecured or make it difficult to lock at all. Address the issue before a minor wiring problem turns into a stranded-vehicle situation.