B1627 — PRNDL Reverse Input Circuit Failure

What does OBD2 code B1627 mean?

PRNDL Reverse Input Circuit Failure (B1627): a body electrical fault affecting the body electrical system. The car is usually drivable while you plan the repair. Most often caused by faulty switch, motor or actuator of the affected system, body control module (BCM) fault, corroded or loose connectors.

What is the most common cause of B1627?

The most common causes are: faulty switch, motor or actuator of the affected system, body control module (BCM) fault, corroded or loose connectors.

How much does it cost to fix B1627?

Repair wiring or connectors — $80–$250; BCM repair or replacement — $300–$900; 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.

Is it safe to drive with B1627?

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.

Will B1627 clear itself?

Sometimes B1627 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 the engine control module (ECM) or body control module (BCM) detects an abnormal signal in the reverse gear input circuit, it logs OBD2 code B1627. This trouble code specifically points to a PRNDL (Park, Reverse, Neutral, Drive, Low) reverse input circuit failure — meaning the system is having trouble confirming that the transmission is in reverse gear. The PRNDL circuit is part of the broader body electrical architecture; it carries position signals from the gear selector switch through wiring and connectors to the BCM, which then relays that information to the ECM.

The ECM does not trigger B1627 after a single bad reading. Most manufacturers require the fault condition to appear repeatedly under specific operating conditions before the module permanently stores the code and turns on the warning light. When B1627 is set, the ECM saves freeze frame data — a snapshot showing engine load, RPM, coolant temperature, and vehicle speed at the exact moment the problem occurred. That data is valuable: replicate those conditions during testing and you will find the fault faster.

Symptoms of B1627

• The check engine light or a dedicated body-system warning lamp illuminates on the dashboard
• In most cases the engine runs and drives normally — B1627 is a body electrical fault, not an engine fault
• The specific function tied to the affected circuit behaves erratically or stops working entirely, such as:
• Power door locks failing to lock or unlock
• Windows not responding to switch commands
• Interior or exterior lights flickering or going out
• Windshield wipers operating intermittently or not at all
• The malfunction may be continuous or appear only under certain conditions (temperature, humidity, or vibration)

Common Causes

• Damaged wiring in door jambs, tailgate hinges, or other areas where flexing occurs — insulation cracks and wire breaks are frequent in these locations
• Corroded, loose, or oil-contaminated connectors creating high resistance or intermittent opens in the circuit
• Blown fuse or failed relay supplying power to the affected circuit
• Faulty switch, motor, or actuator within the component that the circuit controls
• Body control module (BCM) internal failure — less common but possible, especially on higher-mileage vehicles
• Water intrusion into wiring or connectors from leaks, car washes, or condensation, leading to short circuits or corrosion
• Chafed wiring from rubbing against sharp metal edges or routing through areas with excessive vibration

How to Diagnose B1627

1. Connect an OBD2 scanner and confirm that B1627 is stored in the ECM. Record the freeze frame data — note the engine load, RPM, coolant temperature, and vehicle speed recorded when the fault first appeared. Those values tell you what conditions to reproduce during your road test.
2. Check for related diagnostic trouble codes. B1627 often appears alongside other body-system codes. Intermittent faults in one circuit can cascade into adjacent ones, so identifying the root code first saves diagnostic time. Also search for manufacturer TSBs (technical service bulletins) for your make and model — many B0xxx-series codes have documented factory fixes or BCM software updates.
3. Visually inspect the wiring harness and connectors associated with the body electrical system. Look for damaged insulation, dark discoloration from heat, green or white corrosion deposits, and any connectors that are not fully seated. Pay extra attention to the areas behind interior trim panels and under the hood where wiring passes through bulkheads.
4. Operate the affected component (locks, windows, lights, wipers) while monitoring live data on the scanner. Compare the switch input PID and motor output PID against expected values. A switch that shows correct state on the scanner but produces no motor action points to a power or ground problem downstream.
5. Inspect connectors and wiring at flex points — door jambs, hood hinges, tailgate openings — where wires bend repeatedly. These are the most likely spots for broken strands inside the insulation. Tug gently on suspect wires; a broken wire will often pull apart or feel mushy.
6. Clear the code and complete a full drive cycle that includes the operating conditions captured in the freeze frame. Recheck for B1627 on the scanner. If the code does not return, the fault was likely a temporary condition. If it returns, continue testing the circuit until the defective component is identified.

Repair Options and Costs

The appropriate repair depends entirely on which part of the circuit is faulty. Independent shop labor rates typically range from $75 to $125 per hour depending on location.

• Wiring repair or connector replacement: Repairing damaged wires, soldering connections, or replacing corroded connectors usually costs between $80 and $250 including labor and minor parts.
• BCM repair or replacement: If the body control module itself has failed internally, repair or replacement runs $300 to $900 depending on whether the module can be rebuilt or must be replaced with a new or used unit.
• Switch or actuator replacement: Replacing a faulty switch, motor, or actuator in the affected circuit typically costs between $120 and $450 depending on the part price and labor time.

How Much Does Fixing B1627 Cost Overall?

Total repair costs for B1627 typically fall between $80 and $900. The wide range reflects how much circuit investigation is needed before the actual failure point is found. Always pursue the cheapest probable causes — wiring and connectors — before committing to BCM replacement, which is the most expensive scenario. A thorough diagnosis upfront prevents spending $900 on a new module when a $15 connector or a $30 fuse was the real culprit all along.

Can You Drive with B1627?

Yes — B1627 is classified as a body electrical fault and does not directly affect engine performance, transmission shifting, or drivability. Most vehicles remain fully driveable when this code is present. However, the associated system failure can create safety concerns in specific situations. If the malfunction involves exterior lighting, you lose visibility at night or in poor weather. Non-functional wipers become a hazard during rain or snow. A central locking system that fails intermittently can leave the vehicle unsecured. Address these issues promptly, but there is no immediate risk of mechanical damage or being stranded on the roadside.