B1733 — Mirror Driver Vertical Switch Circuit Failure

The diagnostic trouble code B1733 indicates a malfunction or failure in the vertical adjustment switch circuit of the driver’s side mirror. This code is typically set when the vehicle’s Electronic Control Unit (ECU), which manages various comfort and safety features, detects an inconsistency or fault in the wiring or signal of the mirror’s vertical adjustment switch. It’s important to note that labeling of this code can differ between OEMs (Original Equipment Manufacturers), so variations may occur depending on the vehicle make and model.

Manufacturer variations for trouble code B1733

Many vehicle manufacturers use different diagnostic labels or code numbers for similar issues involving the mirror adjustment circuit. These labels can vary depending on the brand’s coding conventions, but often refer to similar circuit or switch faults related to the side mirrors. Examples of known variations include:

• Volkswagen Group (VW, Audi, Skoda, Seat): 00533
• BMW: 005C
• Mercedes-Benz: 212A
• Honda: 42-01
• Toyota: C1559
• Ford: U230

It is essential to consult the specific manufacturer’s workshop manual or diagnostic software to cross-reference the exact label or code used for this particular issue in the vehicle being serviced.

What does trouble code B1733 mean?

B1733 is a generic OBD-II (On-Board Diagnostics — Second Generation) trouble code that points to a fault within the driver’s side mirror vertical adjustment switch circuit. The vehicle’s ECU constantly monitors various circuits and components to ensure they operate correctly. When it detects an abnormality or interruption—such as a short circuit, broken wiring, or a faulty switch—it records this fault as a DTC (Diagnostic Trouble Code).

Specifically, this code indicates that the ECU has identified an issue with the electrical circuit that controls the vertical movement function of the driver’s mirror. The switch responsible for this function might not be sending a consistent signal, or the circuit wiring may have been damaged or disconnected.

This fault is often noticed when the driver attempts to adjust the mirror vertically and finds that the control is unresponsive or behaves erratically. The code can also appear as part of a diagnostic routine after a vehicle’s electrical system has been checked or during an active fault warning on the dashboard.

Severity and risks of trouble code B1733

The severity of B1733 is generally considered moderate. While it does not typically affect the overall safety or drivability of the vehicle, it does impair a key comfort feature — the vertical adjustment of the driver’s side mirror.

The main risks associated with this fault include:

• Inability to correctly position the driver’s mirror, which can impact visibility and safety, especially in poor weather or low-light conditions.
• Potential for electrical issues if the fault is caused by a wiring short or severe circuit problem.
• Possible deterioration of other related mirror functions if the wiring or switches are damaged or deteriorating.

Overall, Limited — can the vehicle be driven? Yes. The vehicle remains safely drivable, but the driver’s visibility adjustment features are compromised until the fault is repaired.

Symptoms of trouble code B1733

The presence of B1733 can manifest through various symptoms, primarily relating to the malfunction of the driver’s side mirror. These symptoms may include:

• Failure of the vertical adjustment control on the driver’s mirror switch — it may be unresponsive.
• Unusual behavior when attempting to adjust the mirror, such as erratic or no movement despite switch operation.
• Possible warning lights or messages appearing on the dashboard related to mirror or electrical faults.
• In some cases, the mirror may move randomly or not at all, impacting driver visibility.
• Potential intermittent functioning of other mirror-related electrical features if wiring or connectors are involved.

Most likely causes of trouble code B1733

Several factors can lead to the activation of the B1733 code. Typically, the root causes stem from issues involving wiring, switches, or the circuit components responsible for mirror control. The most common causes are ranked as follows:

1. Faulty or worn switch — The vertical adjustment switch itself may be defective or have developed internal failures, preventing proper signal transmission.
2. Damaged wiring or connectors — Corrosion, wear, or physical damage to the wiring harness connecting the mirror switch to the vehicle’s ECU can interrupt the signal flow.
3. Electrical short circuit or open circuit — A short or open in the wiring may trigger the error, often caused by moisture ingress or physical impacts.
4. Malfunctioning mirror control module — In some vehicles, a dedicated module might control mirror functions; if faulty, it can cause this code.
5. Software or calibration issues — Rarely, a software glitch in the ECU or incorrect configuration may generate false fault codes.

How to diagnose trouble code B1733

Diagnosing B1733 involves systematic checks to identify the faulty component or connection. Here are generic diagnostic steps suitable for most vehicles:

1. Visual inspection: Check the wiring harness and connectors leading to the driver’s side mirror switch for signs of damage, corrosion, or disconnection.
2. Test switch operation: Using a multimeter or vehicle-specific diagnostic tool, verify that the mirror adjustment switch functions correctly when operated.
3. Check for continuity: Perform a continuity test on the wires connecting the switch to the ECU to ensure there are no open circuits or shorts.
4. Scan live data: Use an OBD-II scanner or manufacturer-specific diagnostic tool to monitor the mirror switch signals in real-time, confirming proper communication.
5. Inspect the mirror motor and mechanism: Verify the operational status of the mirror motor to rule out mechanical issues that could mimic electrical faults.
6. Reset and test: Clear the fault code and test the system again to see if it reappears, indicating a persistent issue.

Possible repairs for trouble code B1733

Based on identified root causes, several repairs can be undertaken. Some repairs are straightforward, while others may require professional intervention.

• Replace the faulty switch: If the switch itself is defective, replacing it is a common repair, typically performed by a qualified technician.
• Repair or replace wiring and connectors: Damaged wiring harnesses or corroded connectors should be repaired or replaced to restore proper circuit continuity. This is best performed by professionals.
• Address short or open circuits: Identifying and fixing wiring shorts or opens may involve repairing insulation or replacing damaged wiring sections.
• Update or reconfigure ECU software: If software issues are suspected, a vehicle software update or reprogramming may be necessary, requiring specialist diagnostic tools.
• Replace mirror control module: In some cases, the module managing mirror functions could be at fault and may need replacement, best done by a professional.

Vehicles commonly associated with trouble code B1733 in Europe

While the code B1733 can appear in numerous makes and models, certain brands and models in Europe are more frequently reported with this fault, particularly those with electric mirrors as standard or optional features.

Examples grouped by manufacturer include:

Volkswagen Group (VW, Audi, Škoda, Seat):

• Volkswagen Golf, Passat, Tiguan
• Audi A3, A4, Q3
• Škoda Octavia, Superb
• Seat Leon, Ateca

BMW:

• Series 1, 3, 5, X Series

Mercedes-Benz:

• C-Class, E-Class, GLC

Other brands (less common but possible):

• Honda Civic, CR-V
• Toyota Corolla, RAV4
• Ford Focus, Kuga

In Europe, the presence of electric or power-adjustable side mirrors is more prevalent, increasing the likelihood of encountering this fault in these models.

Frequent mistakes with trouble code B1733

When diagnosing or repairing B1733, technicians and DIY enthusiasts often make some common errors. Awareness of these pitfalls can improve diagnostic accuracy and avoid unnecessary repairs:

• Ignoring the wiring harness: Neglecting detailed inspection of wiring connectors and circuits is a frequent mistake that may lead to misdiagnosis.
• Replacing only the switch without testing: Assuming the switch is faulty without verifying its operation can result in unnecessary part replacement.
• Overlooking software issues: Sometimes, the problem may stem from ECU software glitches that require reprogramming, which is often overlooked.
• Misinterpreting intermittent fault codes: Faults that appear sporadically can be misdiagnosed if live data isn’t monitored properly.
• Assuming the fault is in the mirror motor: Mechanical issues with the mirror’s movement are less common, so electrical diagnosis should be prioritized first.

FAQ — trouble code B1733

Can this code disappear on its own?

It’s uncommon for B1733 to resolve spontaneously. Typically, the fault persists unless the underlying issue (such as wiring damage or switch failure) is repaired. Occasionally, temporary electrical glitches may clear temporarily, but the problem often reappears.

Can I keep driving?

Yes. The vehicle remains safe to drive, as this code does not generally affect core driving functions. However, the driver’s ability to adjust the mirror vertically may be temporarily limited until repairs are completed for optimal visibility and safety.

Why does the code return after clearing?

The fault likely remains unresolved. Causes such as wiring problems, a faulty switch, or a malfunctioning control module can trigger the code to reappear once the ECU re-runs its checks during vehicle operation. Proper diagnosis and repair are essential to prevent recurrence.