B1238 – OBD-II DTC

OBD-II DTC B1238 – Over Temperature Fault

DTC B1238 meaning

DTC B1238 refers to an Over Temperature Fault detected in the vehicle’s onboard diagnostic system. This code indicates that a specific component, often related to the climate control system or air conditioning, has exceeded its normal operating temperature range. The vehicle’s computer monitors various sensors, and when it identifies a temperature that is too high, it triggers this diagnostic trouble code (DTC) to alert the technician of a potential issue.

DTC B1238 symptoms

Common symptoms associated with DTC B1238 may include:

• Increased cabin temperature or inadequate cooling
• Air conditioning system malfunction
• Warning lights illuminated on the dashboard
• Unusual noises from the climate control system
• System shutdown or failure to operate

DTC B1238 causes

Several factors can lead to the triggering of DTC B1238, including:

• Faulty temperature sensors
• Blocked or restricted airflow in the cooling system
• Low refrigerant levels in the air conditioning system
• Electrical issues, such as short circuits or open circuits
• Malfunctioning climate control module

DTC B1238 seriousness

DTC B1238 is considered a moderate to serious issue, as it can affect the comfort and safety of the vehicle’s occupants. If the climate control system is not functioning properly, it may lead to overheating of other components, which can result in further damage and costly repairs. It is advisable to address this code promptly to prevent additional complications.

How to diagnose DTC B1238

To diagnose DTC B1238, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the DTC.
2. Check for any additional trouble codes that may provide more context.
3. Inspect the vehicle’s temperature sensors for damage or disconnection.
4. Examine the air conditioning system for refrigerant levels and leaks.
5. Test the climate control module for proper operation.
6. Check for any airflow restrictions in the cooling system.

How to fix DTC B1238 step-by-step instructions

To fix DTC B1238, follow these step-by-step instructions:

1. Confirm the DTC using an OBD-II scanner.
2. Inspect and replace any faulty temperature sensors.
3. Repair or replace any damaged wiring or connectors related to the climate control system.
4. Ensure the air conditioning system is properly charged with refrigerant.
5. Clear any obstructions in the airflow, such as debris or blockages.
6. Test the climate control system to ensure it operates within normal temperature ranges.
7. Re-scan the system to verify that the DTC has been cleared.

How to erase DTC B1238

To erase DTC B1238, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn on the ignition without starting the engine.
3. Navigate to the “Erase Codes” or “Clear DTCs” option on the scanner.
4. Confirm the action to clear the trouble codes.
5. Disconnect the scanner and start the vehicle to ensure the code does not reappear.

Recommended tools for OBD-II diagnostics

Explore our expert picks: The Best OBD2 Scanners for 2025

Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter

Some of the links on this page may be affiliate links, which means we may earn a small commission if you make a purchase. This helps us keep our DTC database up to date and provide valuable content for free. We only recommend products that we have tested and believe to be the best in their class.