For owners of vehicles manufactured between 2004 and 2007, encountering OBD2 codes can be a common part of vehicle maintenance. Among these, codes C0163, C0164, and C0278 signal potential issues within the braking system, specifically pointing towards the Brake Pedal Position (BPP) sensor. This sensor is crucial for various safety systems in your vehicle, including the Anti-lock Braking System (ABS), Traction Control System (TCS), and Vehicle Stability Enhancement System (VSES). Understanding these 2004 To 2007 Obd2 Codes is the first step in ensuring your vehicle’s safety and performance are maintained.
This article delves into these specific OBD2 codes, providing you with a clear understanding of what they mean, their potential causes, and how they can be addressed. We aim to empower you with the knowledge to discuss these issues effectively with your mechanic or to undertake initial troubleshooting if you are a DIY enthusiast.
Understanding OBD2 Code C0163: ABS/TCS/Brake Switch Sensor Circuit Low
OBD2 code C0163 is described as “ABS/TCS/Brake Switch Sensor Circuit Low”. This diagnostic trouble code indicates that the Electronic Brake Control Module (EBCM) is detecting a low voltage condition in the brake pedal position sensor circuit. The BPP sensor is a potentiometer that receives a 5-volt reference signal from the Body Control Module (BCM). Code C0163 is triggered when the EBCM perceives that the voltage signal from the BPP sensor is not within the expected range, specifically when it’s between 1.87 volts and 5.03 volts for a continuous 2-second period while the ignition is ON.
Symptoms of C0163:
When OBD2 code C0163 is set, you may experience the following symptoms:
- Service Traction System and Service Active Handling messages displayed on the Driver Information Center (DIC).
- Traction Control and Active Handling indicator lights will illuminate on the dashboard.
- TCS/VSES will be disabled for the current ignition cycle (if your vehicle is equipped with these systems).
- ABS remains functional, as the primary braking system is still operational.
Possible Causes of C0163:
Several factors can lead to OBD2 code C0163. Troubleshooting should consider these potential issues:
- Open Circuit in the BPP Sensor Signal Wire: A break or disconnection in the signal wire leading from the BPP sensor to the EBCM.
- BPP Sensor Calibration Issues: The brake pedal position sensor might require calibration to ensure it’s sending the correct signals.
- Open Circuit in All Brake Lamps: If all brake lights are not functioning due to an open circuit, it can affect the BPP sensor reading.
- Open Ground for All Brake Lamps: Similarly, a lack of proper ground for all brake lamps can also cause this code.
- Internal EBCM Problem: In less frequent cases, the EBCM itself might be faulty.
 for two consecutive ignition cycles, the EBCM will set this code. This is often checked when the vehicle speed exceeds 25 mph (40 km/h).
Symptoms of C0164:
Similar to C0163, the symptoms for OBD2 code C0164 will include:
- Service Traction System and Service Active Handling alerts appearing on the DIC.
- Traction Control and Active Handling warning lights illuminating on the instrument panel.
- TCS/VSES being disabled for the duration of the ignition cycle.
- ABS functionality remains unaffected, ensuring standard braking is still available.
Possible Causes of C0164:
The causes for OBD2 code C0164 usually involve issues that lead to a high voltage reading from the BPP sensor:
- Short to Voltage in BPP Sensor Circuit: The most common cause is a short circuit where the BPP sensor circuit is unintentionally receiving voltage from another source.
- Misadjusted Brake Pedal Position Sensor: If the BPP sensor is not correctly adjusted, it can send an incorrect high voltage signal even when the brake pedal is not engaged.
- BPP Sensor Stuck Closed: A malfunction within the sensor itself might cause it to be stuck in a ‘closed’ position, constantly signaling brake application.
- Binding Brake Pedal: A mechanically binding brake pedal can also lead to incorrect readings from the BPP sensor, potentially triggering a high voltage signal.
 will illuminate.
- Engine Drive Control is disabled, which might lead to reduced engine power or prevent the engine from starting in some cases.
- Panic Brake Assist is disabled, potentially reducing the effectiveness of emergency braking.
- Traction Control System (TCS) is disabled, impacting vehicle stability during acceleration and cornering.
- Vehicle Stability Enhancement System (VSES) is disabled, further compromising overall vehicle stability and handling, especially in challenging driving conditions.
Possible Causes of C0278:
OBD2 code C0278 arises directly from issues related to the BPP sensor calibration:
- BPP Sensor Calibration Not Performed: This is common after replacing the BPP sensor or the EBCM, as a new sensor or module needs to be calibrated to the vehicle.
- Unsuccessful BPP Sensor Calibration: If a calibration procedure was attempted but failed for any reason, this code will be set.
Clearing and Addressing C0278:
Unlike C0163 and C0164 which might clear themselves once the underlying issue is resolved, C0278 typically requires a manual clearing process after calibration.
- Calibration Procedure Required: The primary solution for C0278 is to perform a brake pedal position sensor calibration procedure. This usually involves using a diagnostic scan tool to initiate and complete the calibration process as per the vehicle manufacturer’s instructions.
- Clearing DTC with Scan Tool: After successful calibration, the current DTC C0278 should be cleared using a scan tool.
- History DTC Clearing: If the current DTC is cleared, a history DTC (if stored) will automatically clear after 100 consecutive ignition cycles without the fault reoccurring.
 sensor. This sensor plays a vital role in the functionality of your vehicle’s safety systems, including ABS, Traction Control, and Stability Control. Ignoring these 2004 to 2007 OBD2 codes can lead to compromised safety and reduced vehicle performance.
This guide provides a detailed look at these OBD2 codes, explaining their meaning, symptoms, potential causes, and troubleshooting steps. Whether you’re a car owner looking to understand your vehicle better or a seasoned mechanic, this information will help you diagnose and resolve these BPP sensor-related issues effectively.
OBD2 Code C0163: Brake Pedal Position Sensor Circuit Low
The OBD2 code C0163, defined as “Brake Pedal Position Sensor Circuit Low,” indicates that the vehicle’s Electronic Brake Control Module (EBCM) is registering an abnormally low voltage within the brake pedal position sensor circuit. The BPP sensor is designed as a potentiometer, receiving a consistent 5-volt reference signal, typically from the Body Control Module (BCM). The EBCM triggers code C0163 when it detects that the voltage signal from the BPP sensor falls outside the expected operating range, specifically remaining between 1.87 and 5.03 volts for a continuous duration of 2 seconds while the ignition is in the “ON” position.
Recognizing the Symptoms of C0163:
When OBD2 code C0163 activates, you may observe several symptoms:
- Dashboard Warning Lights: The “Service Traction System” and “Service Active Handling” messages might appear on your vehicle’s Driver Information Center (DIC). Additionally, the Traction Control and Active Handling indicator lights on the dashboard will illuminate.
- Disabled Safety Systems: If your vehicle is equipped with Traction Control System (TCS) and Vehicle Stability Enhancement System (VSES), these systems will be temporarily disabled for the current ignition cycle.
- ABS Remains Functional: Importantly, the Anti-lock Braking System (ABS) will continue to operate normally, ensuring basic braking functionality is maintained.
Pinpointing the Causes of C0163:
Several potential issues can trigger OBD2 code C0163. When troubleshooting, consider these common causes:
- Signal Circuit Open: An open or break in the signal wire connecting the BPP sensor to the EBCM is a primary suspect. This interruption prevents proper signal transmission.
- Sensor Calibration Needed: The BPP sensor itself might require calibration. If it’s not correctly calibrated, it may send inaccurate voltage signals, leading to a false “low voltage” reading.
- Brake Lamp Circuit Issues: Problems with the brake lamp circuit can indirectly affect the BPP sensor reading. Specifically, an open circuit in all brake lamps or a missing ground for all brake lamps can contribute to this code.
- EBCM Malfunction: Although less common, an internal fault within the EBCM itself could be the root cause of the erroneous low voltage reading.
OBD2 Code C0164: Brake Pedal Position Sensor Circuit High
OBD2 code C0164, known as “ABS/TCS/Brake Switch Sensor Circuit High,” is set when the EBCM detects an unusually high voltage signal originating from the brake pedal position sensor circuit. In contrast to C0163, which signals a low voltage issue, C0164 indicates that the voltage signal is excessively high. This code is typically activated if the BPP sensor input remains active (indicating high voltage) for two consecutive ignition cycles, especially when the vehicle’s speed exceeds 25 mph (40 km/h).
Identifying the Symptoms of C0164:
Similar to code C0163, OBD2 code C0164 presents with the following symptoms:
- Warning Messages on DIC: The Driver Information Center (DIC) may display “Service Traction System” and “Service Active Handling” messages.
- Dashboard Indicator Lights: The Traction Control and Active Handling warning lights will light up on the dashboard.
- Safety System Disablement: The Traction Control System (TCS) and Vehicle Stability Enhancement System (VSES) will be deactivated for the current ignition cycle.
- ABS Functionality Maintained: The Anti-lock Braking System (ABS) will remain operational, ensuring standard braking capabilities are preserved.
Determining the Causes of C0164:
The causes of OBD2 code C0164 usually involve conditions that lead to an elevated voltage reading from the BPP sensor:
- Short to Voltage: The most frequent cause is a short circuit where the BPP sensor circuit inadvertently receives voltage from another electrical source, artificially inflating the voltage reading.
- Sensor Misadjustment: If the brake pedal position sensor is improperly adjusted, it can transmit an erroneously high voltage signal, even when the brake pedal is not being pressed.
- Stuck Sensor: Internal sensor failure can cause the BPP sensor to become stuck in a ‘closed’ position, constantly signaling brake application and resulting in a high voltage signal.
- Brake Pedal Binding: Mechanical issues such as a binding brake pedal can also lead to inaccurate readings from the BPP sensor, potentially triggering a high voltage signal and setting code C0164.
OBD2 Code C0278: Brake Pedal Position Sensor Calibration Not Calibrated
OBD2 code C0278, labeled “Brake Pedal Position Sensor Not Calibrated,” is distinct from C0163 and C0164 because it doesn’t point to a circuit malfunction, but rather to a sensor calibration problem. This code is triggered when the EBCM recognizes that the brake pedal position sensor has not been calibrated or that the last calibration attempt was unsuccessful. The EBCM continuously monitors for this condition whenever it is powered.
Recognizing the Symptoms of C0278:
The implications of OBD2 code C0278 are more serious as it directly affects vehicle performance and critical safety systems. When this code is active, expect the following:
- Check Engine Light: The “Service Vehicle Soon lamp” (check engine light) will illuminate, indicating a system malfunction.
- Engine Drive Control Disabled: Engine drive control may be disabled, leading to reduced engine power or even preventing the engine from starting.
- Panic Brake Assist Disabled: The effectiveness of panic or emergency braking might be diminished due to the deactivation of panic brake assist.
- Traction Control and Stability Control Disabled: Both the Traction Control System (TCS) and the Vehicle Stability Enhancement System (VSES) will be disabled, significantly impacting vehicle stability and handling, especially in challenging driving conditions.
Identifying the Causes of C0278:
OBD2 code C0278 is directly related to issues with the BPP sensor’s calibration status:
- Calibration Not Initiated: This is a common occurrence after replacing the BPP sensor or the EBCM. New components require calibration to communicate correctly with the vehicle’s system.
- Calibration Failure: If the calibration procedure was attempted but did not complete successfully, this code will be set. Calibration can fail due to various reasons, including incorrect procedure, faulty scan tool, or sensor issues.
Resolving OBD2 Code C0278:
Unlike codes C0163 and C0164, which may self-clear after the underlying fault is fixed, C0278 typically requires a manual clearing procedure following successful calibration.
- Calibration Procedure is Essential: The primary solution for C0278 is to perform a proper brake pedal position sensor calibration. This process usually requires a professional-grade diagnostic scan tool to initiate and complete the calibration according to the vehicle manufacturer’s specific instructions.
- DTC Clearing with Scan Tool: Once the calibration is successfully completed, it’s necessary to clear the current DTC C0278 using the scan tool. This confirms to the vehicle’s computer that the issue has been addressed.
- Automatic History DTC Clearing: After clearing the current DTC, any stored history DTC related to C0278 will automatically clear after approximately 100 consecutive ignition cycles, provided the fault does not reappear.
By understanding these 2004 to 2007 OBD2 codes and their implications, you can better address potential braking system issues in your vehicle, ensuring continued safety and optimal performance. If you are not comfortable performing these diagnostic and repair procedures yourself, it is always recommended to consult a qualified mechanic.
