Not all OBDII codes cause an engine light, OBD codes or DTC (diagnostic trouble code) are stored by the ECU (Engine Control Unit) or PCM (Powertrain Control Module) to point the mechanic to the cause.  The engine light is an indicator of problems.  The engine light on its own does not provide details, but reading the stored DTC is a good pointer to where the issue is.

If a DTC is stored in your ECU, it doesn’t necessary mean that there will be an engine light.  In fact no other indicator may be present.  The engine light is typically reserved for drivability or emission problems.  If you’re a DIY person, you should invest in a good OBDII scanner, now available with bluetooth.

Looking for Recalls:

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OBD / OBDII DTC stored in the ECU (May be causing an engine light):

1. Body Codes (B0XXX – B3XXX)
   • B0100 – B0199: Airbags, Seat Belts
   • B0200 – B0299: Body Control Modules, Windows, Doors

Body Codes B0100 – B0199

• B0100 – Air Bag Sensor Assembly Malfunction
  • causes: Faulty airbag sensor assembly, wiring or connector, airbag control module problems.
• B0101 – Open in Driver-Side Air Bag Module Squib Circuit
  • causes: Open circuit, faulty driver-side airbag module, wiring or connector.
• B0102 – Short in Driver-Side Air Bag Module Squib Circuit
  • causes: Short circuit, faulty driver-side airbag module, wiring.
• B0103 – Short to GND in Driver-Side Air Bag Module Squib Circuit
  • causes: Short circuit, faulty driver-side airbag module, wiring.
• B0104 – Short to B+ in Driver-Side Air Bag Module Squib Circuit
  • causes: Short circuit, faulty driver-side airbag module, wiring.
• B0105 – Open in Passenger-Side Air Bag Module Squib Circuit
  • causes: Open circuit, faulty passenger-side airbag module, wiring or connector.
• B0106 – Short in Passenger-Side Air Bag Module Squib Circuit
  • causes: Short circuit, faulty passenger-side airbag module, wiring.
• B0107 – Short to GND in Passenger-Side Air Bag Module Squib Circuit
  • causes: Short circuit, faulty passenger-side airbag module, wiring.
• B0108 – Short to B+ in Passenger-Side Air Bag Module Squib Circuit
  • causes: Short circuit, faulty passenger-side airbag module, wiring.
• B0109 – Short to GND in Front Passenger’s Side Air Bag Module Squib Circuit
  • causes: Short circuit, faulty front passenger-side airbag module, wiring.

OBD / OBDII DTC B0110 – B0119

• B0110 – Short to B+ in Front Passenger’s Side Air Bag Module Squib Circuit
  • causes: Short circuit, faulty front passenger-side airbag module, wiring.
• B0111 – Open in Side Squib (LH) Circuit
  • causes: Open circuit, faulty side airbag module, wiring or connector.
• B0112 – Short in Side Squib (LH) Circuit
  • causes: Short circuit, faulty side airbag module, wiring.
• B0113 – Short to GND in Side Squib (LH) Circuit
  • causes: Short circuit, faulty side airbag module, wiring.
• B0114 – Short to B+ in Side Squib (LH) Circuit
  • causes: Short circuit, faulty side airbag module, wiring.
• B0115 – Open in Side Squib (RH) Circuit
  • causes: Open circuit, faulty side airbag module, wiring or connector.
• B0116 – Short in Side Squib (RH) Circuit
  • causes: Short circuit, faulty side airbag module, wiring.
• B0117 – Short to GND in Side Squib (RH) Circuit
  • causes: Short circuit, faulty side airbag module, wiring.
• B0118 – Short to B+ in Side Squib (RH) Circuit
  • causes: Short circuit, faulty side airbag module, wiring.
• B0119 – Center Airbag Sensor Assembly Malfunction
  • causes: Faulty center airbag sensor assembly, wiring or connector, airbag control module.

OBD / OBDII DTC B0120 – B0129

• B0120 – Left Curtain Shield Squib Malfunction
  • causes: Faulty left curtain shield airbag, wiring or connector.
• B0121 – Right Curtain Shield Squib Malfunction
  • causes: Faulty right curtain shield airbag, wiring or connector.
• B0122 – Driver Side Airbag Squib Malfunction
  • causes: Faulty driver-side airbag, wiring or connector.
• B0123 – Front Passenger Side Airbag Squib Malfunction
  • causes: Faulty passenger-side airbag, wiring or connector.
• B0124 – Left Side Airbag Squib Malfunction
  • causes: Faulty left side airbag, wiring or connector.
• B0125 – Right Side Airbag Squib Malfunction
  • causes: Faulty right side airbag, wiring or connector.
• B0126 – Curtain Shield Airbag Squib LH Circuit Malfunction
  • causes: Faulty left-hand curtain shield airbag, wiring or connector.
• B0127 – Curtain Shield Airbag Squib RH Circuit Malfunction
  • Common causes: Faulty right-hand curtain shield airbag, wiring or connector.
• B0128 – Center Airbag Sensor Assembly Communication Circuit Malfunction
  • causes: Communication issues, faulty center airbag sensor assembly, wiring.
• B0129 – Seatbelt Buckle Switch LH Circuit Malfunction
  • causes: Faulty seatbelt buckle switch, wiring or connector.

OBD / OBDII DTC B0130 – B0139

• B0130 – Seatbelt Buckle Switch RH Circuit Malfunction
  • causes: Faulty seatbelt buckle switch, wiring or connector.
• B0131 – Front Seatbelt Buckle Switch LH Circuit Malfunction
  • causes: Faulty seatbelt buckle switch, wiring or connector.
• B0132 – Front Seatbelt Buckle Switch RH Circuit Malfunction
  • causes: Faulty seatbelt buckle switch, wiring or connector.
• B0133 – Rear Seatbelt Buckle Switch LH Circuit Malfunction
  • causes: Faulty seatbelt buckle switch, wiring or connector.
• B0134 – Rear Seatbelt Buckle Switch RH Circuit Malfunction
  • causes: Faulty seatbelt buckle switch, wiring or connector.
• B0135 – Seatbelt Pretensioner Squib Circuit Malfunction
  • causes: Faulty seatbelt pretensioner, wiring or connector.
• B0136 – Seatbelt Pretensioner Squib Circuit Open
  • causes: Open circuit, faulty seatbelt pretensioner, wiring or connector.
• B0137 – Seatbelt Pretensioner Squib Circuit Short to Battery
  • causes: Short circuit, faulty seatbelt pretensioner, wiring.
• B0138 – Seatbelt Pretensioner Squib Circuit Short to Ground
  • causes: Short circuit, faulty seatbelt pretensioner, wiring.
• B0139 – Seatbelt Pretensioner Squib Circuit Short to Voltage
  • causes: Electrical fault, faulty seatbelt pretensioner, wiring.

OBD / OBDII DTC B0140 – B0149

• B0140 – Seatbelt Pretensioner Squib Circuit Resistance Low
  • causes: Faulty seatbelt pretensioner, wiring or connector.
• B0141 – Seatbelt Pretensioner Squib Circuit Resistance High
  • causes: Faulty seatbelt pretensioner, wiring or connector.
• B0142 – Seatbelt Pretensioner Squib Circuit Resistance Out of Range
  • causes: Faulty seatbelt pretensioner, wiring or connector.
• B0143 – Seatbelt Load Limiter Circuit
  • causes: Faulty seatbelt load limiter, wiring or connector.
• B0144 – Seatbelt Load Limiter Circuit Open
  • causes: Open circuit, faulty seatbelt load limiter, wiring or connector.
• B0145 – Seatbelt Load Limiter Circuit Short to Battery
  • causes: Short circuit, faulty seatbelt load limiter, wiring.
• B0146 – Seatbelt Load Limiter Circuit Short to Ground
  • causes: Short circuit, faulty seatbelt load limiter, wiring.
• B0147 – Seatbelt Load Limiter Circuit Resistance Low
  • causes: Faulty seatbelt load limiter, wiring or connector.
• B0148 – Seatbelt Load Limiter Circuit Resistance High
  • causes: Faulty seatbelt load limiter, wiring or connector.
• B0149 – Seatbelt Load Limiter Circuit Open/Short to Ground
  • causes: Faulty seatbelt load limiter, wiring or connector.

OBD / OBDII DTC B0150 – B0159

• B0150 – Left Frontal Restraint Sensor Circuit Malfunction
  • causes: Faulty restraint sensor, wiring or connector, airbag control module.
• B0151 – Right Frontal Restraint Sensor Circuit Malfunction
  • causes: Faulty restraint sensor, wiring or connector, airbag control module.
• B0152 – Left Frontal Restraint Sensor Circuit Low Frequency
  • causes: Faulty restraint sensor, wiring.
• B0153 – Right Frontal Restraint Sensor Circuit Low Frequency
  • causes: Faulty restraint sensor, wiring.
• B0154 – Air Bag Driver Inflator Circuit
  • causes: Faulty airbag inflator, wiring or connector.
• B0155 – Air Bag Passenger Inflator Circuit
  • causes: Faulty airbag inflator, wiring or connector, airbag control module.
• B0156 – Air Bag Passenger Inflator Circuit Resistance Low on Squib
  • causes: Faulty airbag inflator, wiring.
• B0157 – Air Bag Passenger Inflator Circuit Resistance High on Squib
  • causes: Faulty airbag inflator, wiring.
• B0158 – Air Bag Passenger Inflator Circuit Short to Battery
  • causes: Short circuit, faulty airbag inflator, wiring.
• B0159 – Air Bag Passenger Inflator Circuit Short to Ground
  • causes: Short circuit, faulty airbag inflator, wiring.

OBD / OBDII DTC B0160 – B0169

• B0160 – Air Bag Passenger Inflator Circuit Open
  • causes: Open circuit, faulty airbag inflator, wiring or connector.
• B0161 – Air Bag Passenger Inflator Circuit Short to Voltage
  • causes: Electrical fault, faulty airbag inflator, wiring.
• B0162 – Air Bag Passenger Circuit Short to Ground
  • causes: Short circuit, faulty airbag or airbag control module, wiring.
• B0163 – Air Bag Passenger Circuit Short to Voltage
  • causes: Electrical fault, faulty airbag or airbag control module, wiring.
• B0164 – Air Bag Driver Circuit Failure
  • causes: Faulty driver airbag, wiring or connector, airbag control module.
• B0165 – Air Bag Passenger Circuit Failure
  • causes: Faulty passenger airbag, wiring or connector, airbag control module.
• B0166 – Air Bag Driver Circuit Short to Ground
  • causes: Short circuit, faulty driver airbag, wiring.
• B0167 – Air Bag Passenger Circuit Short to Ground
  • causes: Short circuit, faulty passenger airbag, wiring.
• B0168 – Air Bag Driver Circuit Short to Voltage
  • causes: Electrical fault, faulty driver airbag, wiring.
• B0169 – Air Bag Passenger Circuit Short to Voltage
  • Common causes: Electrical fault, faulty passenger airbag, wiring.

OBD / OBDII DTC B0170 – B0179

• B0170 – Air Bag Driver Inflator Circuit Resistance Low on Squib
  • causes: Faulty airbag inflator, wiring.
• B0171 – Air Bag Driver Inflator Circuit Resistance High on Squib
  • causes: Faulty airbag inflator, wiring.
• B0172 – Air Bag Passenger Inflator Circuit Resistance Low on Squib
  • causes: Faulty airbag inflator, wiring.
• B0173 – Air Bag Passenger Inflator Circuit Resistance High on Squib
  • causes: Faulty airbag inflator, wiring.
• B0174 – Air Bag Driver Inflator Circuit Open
  • causes: Open circuit, faulty airbag inflator, wiring or connector.
• B0175 – Air Bag Driver Inflator Circuit Short to Voltage
  • causes: Electrical fault, faulty airbag inflator, wiring.
• B0176 – Air Bag Driver Inflator Circuit Short to Ground
  • causes: Short circuit, faulty airbag inflator, wiring.
• B0177 – Air Bag Driver Inflator Circuit Resistance Low
  • causes: Faulty airbag inflator, wiring.
• B0178 – Air Bag Driver Inflator Circuit Resistance High
  • causes: Faulty airbag inflator, wiring.
• B0179 – Air Bag Passenger Inflator Circuit Resistance Low
  • causes: Faulty airbag inflator, wiring.

OBD / OBDII DTC B0180 – B0189

• B0180 – Air Bag Passenger Inflator Circuit Resistance High
  • causes: Faulty airbag inflator, wiring.
• B0181 – Air Bag Passenger Inflator Circuit Open
  • causes: Open circuit, faulty airbag inflator, wiring or connector.
• B0182 – Air Bag Passenger Inflator Circuit Short to Voltage
  • causes: Electrical fault, faulty airbag inflator, wiring.
• B0183 – Air Bag Passenger Inflator Circuit Short to Ground
  • causes: Short circuit, faulty airbag inflator, wiring.
• B0184 – Solar Radiation Sensor Circuit Open
  • causes: Open circuit, faulty solar radiation sensor, wiring or connector.
• B0185 – Solar Radiation Sensor Circuit Short to Voltage
  • causes: Electrical fault, faulty solar radiation sensor, wiring.
• B0186 – Solar Radiation Sensor Circuit Short to Ground
  • causes: Short circuit, faulty solar radiation sensor, wiring.
• B0187 – Solar Radiation Sensor Circuit Performance
  • causes: Faulty solar radiation sensor, wiring problems.
• B0188 – Solar Radiation Sensor Circuit Failure
  • causes: Faulty solar radiation sensor, wiring or connector.
• B0189 – Interior Temperature Sensor Circuit Open
  • causes: Open circuit, faulty interior temperature sensor, wiring or connector.

OBD / OBDII DTC B0190 – B0199

• B0190 – Interior Temperature Sensor Circuit Short to Voltage
  • causes: Electrical fault, faulty interior temperature sensor, wiring.
• B0191 – Interior Temperature Sensor Circuit Short to Ground
  • causes: Short circuit, faulty interior temperature sensor, wiring.
• B0192 – Interior Temperature Sensor Circuit Performance
  • causes: Faulty interior temperature sensor, wiring problems.
• B0193 – Interior Temperature Sensor Circuit Failure
  • causes: Faulty interior temperature sensor, wiring or connector.
• B0194 – Interior Temperature Output Circuit Open
  • causes: Open circuit, faulty interior temperature control system, wiring or connector.
• B0195 – Interior Temperature Output Circuit Short to Voltage
  • causes: Electrical fault, faulty interior temperature control system, wiring.
• B0196 – Interior Temperature Output Circuit Short to Ground
  • causes: Short circuit, faulty interior temperature control system, wiring.
• B0197 – Interior Temperature Output Circuit Performance
  • causes: Faulty interior temperature control system, wiring problems.
• B0198 – Interior Temperature Output Circuit Failure
  • causes: Faulty interior temperature control system, wiring or connector.
• B0199 – Solar Load Sensor Circuit Failure
  • causes: Faulty solar load sensor, wiring or connector, climate control system problems.

Why is my Engine Light on?

On-Board Diagnostic (OBD / OBDII) codes are stored within the Engine Control Unit (ECU) or Powertrain Control Module (PCM). These modules store the codes, monitor and control engine performance and emissions. When the system detects a fault or irregularity, it generates a diagnostic trouble code (DTC), which is stored in the ECU/PCM’s memory. This code can be retrieved using an OBD scanner, providing insights into issues.

What Are These Codes in my ECU?

On-Board Diagnostic (OBD or OBDII ) codes are part of a vehicle’s self-diagnostic system.  The ECU and sensors work together to produce DTCs, sometimes resulting in an engine light.  The codes generated do not always cause an engine light.  The development of OBD systems began in the 1980s, driven by increasing environmental concerns and regulations, especially in California. The California Air Resources Board (CARB) played a key role in this, mandating the first OBD systems.  OBD, introduced in the 1980s, was the first system of its kind.  The evolution of OBD technology culminated in the universal OBDII standard in the mid-1990s.  It provided basic capabilities to monitor and diagnose vehicle functions, primarily for emissions control.  OBDII, introduced in the mid-1990s, is a more advanced and standardized system.  This OBDII advanced system was mandatory for all cars sold in the United States from 1996 onwards.  OBDII offers broader diagnostics, real-time data, and standardization across most vehicles.  This made it easier to diagnose and address issues.  OBDII’s standardized diagnostic trouble codes (DTC) and connector types are much better than the earlier OBD system, making it easier to diagnosis and repair.