List of all OBD Codes in your ECU

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.

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

1. Powertrain Codes (P0XXX, P2XXX, P34XX – P39XX)
   • P0001 – P0099: Fuel and Air Metering
   • P0100 – P0199: Fuel and Air Metering
   • P0200 – P0299: Fuel and Air Metering (Injector Circuit)
   • P0300 – P0399: Ignition System or Misfire
   • P0400 – P0499: Auxiliary Emissions Controls
   • P0500 – P0599: Vehicle Speed Controls and Idle Control System
   • P0600 – P0699: Computer Output Circuit
   • P0700 – P0799: Transmission
   • P0800 – P0899: Transmission
   • P0900 – P0999: clutch and auxiliary emission control
   • P1XXX: Manufacturer-specific codes

Powertrain Codes P0700 – P0709

• P0700 – Transmission Control System Malfunction
  • General malfunction in the transmission control system.
  • causes: Faulty transmission control module (TCM), wiring or connector, transmission mechanical.
• P0701 – Transmission Control System Range/Performance
  • causes: Faulty TCM, incorrect programming, internal transmission mechanical.
• P0702 – Transmission Control System Electrical
  • causes: Electrical faults within the TCM, wiring, solenoid or sensor.
• P0703 – Brake Switch ‘B’ Circuit
  • causes: Faulty brake switch, wiring or connector, ECM or TCM.
• P0704 – Clutch Switch Input Circuit Malfunction
  • causes: Faulty clutch switch, wiring or connector, ECM or TCM.
• P0705 – Transmission Range Sensor Circuit Malfunction (PRNDL Input)
  • causes: Faulty transmission range sensor, wiring or connector, misaligned or damaged sensor.
• P0706 – Transmission Range Sensor Circuit Range/Performance
  • causes: Faulty sensor, wiring, misaligned sensor.
• P0707 – Transmission Range Sensor Circuit Low Input
  • causes: Short to ground, faulty sensor, wiring.
• P0708 – Transmission Range Sensor Circuit High Input
  • causes: Short to power, faulty sensor, wiring.
• P0709 – Transmission Range Sensor Circuit Intermittent
  • causes: Faulty sensor, intermittent electrical connections, wiring.

OBD / OBDII DTC P0710 – P0719

• P0710 – Transmission Fluid Temperature Sensor Circuit Malfunction
  • causes: Faulty transmission fluid temperature sensor, wiring or connector.
• P0711 – Transmission Fluid Temperature Sensor Circuit Range/Performance
  • causes: Faulty sensor, wiring problems, transmission overheating.
• P0712 – Transmission Fluid Temperature Sensor Circuit Low Input
  • causes: Short to ground, faulty sensor, wiring.
• P0713 – Transmission Fluid Temperature Sensor Circuit High Input
  • causes: Short to power, faulty sensor, wiring.
• P0714 – Transmission Fluid Temperature Sensor Circuit Intermittent
  • causes: Faulty sensor, intermittent electrical connections, wiring.
• P0715 – Input/Turbine Speed Sensor Circuit Malfunction
  • causes: Faulty input/turbine speed sensor, wiring or connector, transmission mechanical.
• P0716 – Input/Turbine Speed Sensor Circuit Range/Performance
  • causes: Faulty sensor, wiring, transmission mechanical.
• P0717 – Input/Turbine Speed Sensor Circuit No Signal
  • causes: Faulty sensor, wiring or connector, transmission mechanical.
• P0718 – Input/Turbine Speed Sensor Circuit Intermittent
  • causes: Faulty sensor, intermittent electrical connections, wiring.
• P0719 – Brake Switch ‘B’ Circuit Low
  • causes: Short to ground, faulty brake switch, wiring.

OBD / OBDII DTC P0720 – P0729

• P0720 – Output Speed Sensor Circuit Malfunction
  • causes: Faulty output speed sensor, wiring or connector, transmission mechanical.
• P0721 – Output Speed Sensor Circuit Range/Performance
  • causes: Faulty sensor, wiring, transmission mechanical.
• P0722 – Output Speed Sensor Circuit No Signal
  • causes: Faulty sensor, wiring or connector, transmission mechanical.
• P0723 – Output Speed Sensor Circuit Intermittent
  • causes: Faulty sensor, intermittent electrical connections, wiring.
• P0724 – Brake Switch ‘B’ Circuit High
  • causes: Short to power, faulty brake switch, wiring.
• P0725 – Engine Speed Input Circuit Malfunction
  • causes: Faulty engine speed sensor, wiring or connector, ECM or TCM.
• P0726 – Engine Speed Input Circuit Range/Performance
  • causes: Faulty sensor, wiring, engine mechanical.
• P0727 – Engine Speed Input Circuit No Signal
  • causes: Faulty sensor, wiring or connector, engine mechanical.
• P0728 – Engine Speed Input Circuit Intermittent
  • causes: Faulty sensor, intermittent electrical connections, wiring.
• P0729 – Gear 6 Incorrect Ratio
  • causes: Internal transmission faults, faulty shift solenoids, transmission control module.

OBD / OBDII DTC P0730 – P0739

• P0730 – Incorrect Gear Ratio
  • causes: Internal transmission faults, faulty shift solenoids, transmission control module.
• P0731 – Gear 1 Incorrect Ratio
  • causes: Same as P0730, specific to 1st gear.
• P0732 – Gear 2 Incorrect Ratio
  • causes: Same as P0730, specific to 2nd gear.
• P0733 – Gear 3 Incorrect Ratio
  • causes: Same as P0730, specific to 3rd gear.
• P0734 – Gear 4 Incorrect Ratio
  • causes: Same as P0730, specific to 4th gear.
• P0735 – Gear 5 Incorrect Ratio
  • causes: Same as P0730, specific to 5th gear.
• P0736 – Reverse Incorrect Ratio
  • causes: Internal transmission faults, faulty shift solenoids, transmission control module.
• P0737 – TCM Engine Speed Output Circuit
  • causes: Faulty TCM, wiring or connector, engine or transmission mechanical.
• P0738 – TCM Engine Speed Output Circuit Low
  • causes: Short to ground, faulty TCM, wiring.
• P0739 – TCM Engine Speed Output Circuit High
  • causes: Short to power, faulty TCM, wiring.

OBD / OBDII DTC P0740 – P0749

• P0740 – Torque Converter Clutch Circuit Malfunction
  • causes: Faulty torque converter clutch solenoid, wiring or connector, torque converter or transmission mechanical.
• P0741 – Torque Converter Clutch Circuit Performance or Stuck Off
  • causes: Faulty torque converter clutch solenoid, torque converter, hydraulic problems in transmission, wiring or connector.
• P0742 – Torque Converter Clutch Circuit Stuck On
  • causes: Faulty torque converter clutch solenoid, torque converter problems, transmission valve body.
• P0743 – Torque Converter Clutch Circuit Electrical
  • causes: Wiring or connector, faulty torque converter clutch solenoid, TCM.
• P0744 – Torque Converter Clutch Circuit Intermittent
  • causes: Intermittent electrical connections, faulty torque converter clutch solenoid, wiring.
• P0745 – Pressure Control Solenoid Malfunction
  • causes: Faulty pressure control solenoid, hydraulic problems, wiring or connector.
• P0746 – Pressure Control Solenoid Performance or Stuck Off
  • causes: Faulty solenoid, transmission fluid, valve body.
• P0747 – Pressure Control Solenoid Stuck On
  • causes: Faulty solenoid, hydraulic blockages, transmission mechanical.
• P0748 – Pressure Control Solenoid Electrical
  • causes: Wiring or connector, faulty solenoid, TCM.
• P0749 – Pressure Control Solenoid Intermittent
  • causes: Intermittent electrical connections, faulty solenoid, wiring.

OBD / OBDII DTC P0750 – P0759

• P0750 – Shift Solenoid ‘A’ Malfunction
  • causes: Faulty shift solenoid, transmission fluid, valve body problems, wiring or connector.
• P0751 – Shift Solenoid ‘A’ Performance or Stuck Off
  • causes: Same as P0750.
• P0752 – Shift Solenoid ‘A’ Stuck On
  • causes: Same as P0750.
• P0753 – Shift Solenoid ‘A’ Electrical
  • causes: Wiring or connector, faulty shift solenoid, TCM.
• P0754 – Shift Solenoid ‘A’ Intermittent
  • causes: Intermittent electrical connections, faulty solenoid, wiring.
• P0755 – Shift Solenoid ‘B’ Malfunction
  • causes: Faulty shift solenoid, transmission fluid, valve body problems, wiring or connector.
• P0756 – Shift Solenoid ‘B’ Performance or Stuck Off
  • causes: Same as P0755.
• P0757 – Shift Solenoid ‘B’ Stuck On
  • causes: Same as P0755.
• P0758 – Shift Solenoid ‘B’ Electrical
  • causes: Wiring or connector, faulty shift solenoid, TCM.
• P0759 – Shift Solenoid ‘B’ Intermittent
  • causes: Intermittent electrical connections, faulty solenoid, wiring.

OBD / OBDII DTC P0760 – P0769

• P0760 – Shift Solenoid ‘C’ Malfunction
  • causes: Faulty shift solenoid, transmission fluid, valve body problems, wiring or connector.
• P0761 – Shift Solenoid ‘C’ Performance or Stuck Off
  • Performance issue or shift solenoid ‘C’ is stuck off.
  • causes: Same as P0760.
• P0762 – Shift Solenoid ‘C’ Stuck On
  • causes: Same as P0760.
• P0763 – Shift Solenoid ‘C’ Electrical
  • causes: Wiring or connector, faulty shift solenoid, TCM.
• P0764 – Shift Solenoid ‘C’ Intermittent
  • causes: Intermittent electrical connections, faulty solenoid, wiring.
• P0765 – Shift Solenoid ‘D’ Malfunction
  • causes: Faulty shift solenoid, transmission fluid, valve body problems, wiring or connector.
• P0766 – Shift Solenoid ‘D’ Performance or Stuck Off
  • Performance issue or shift solenoid ‘D’ is stuck off.
  • causes: Same as P0765.
• P0767 – Shift Solenoid ‘D’ Stuck On
  • causes: Same as P0765.
• P0768 – Shift Solenoid ‘D’ Electrical
  • causes: Wiring or connector, faulty shift solenoid, TCM.
• P0769 – Shift Solenoid ‘D’ Intermittent
  • causes: Intermittent electrical connections, faulty solenoid, wiring.

OBD / OBDII DTC P0770 – P0779

• P0770 – Shift Solenoid ‘E’ Malfunction
  • Common causes: Faulty shift solenoid, transmission fluid, valve body problems, wiring or connector.
• P0771 – Shift Solenoid ‘E’ Performance or Stuck Off
  • Performance issue or shift solenoid ‘E’ is stuck off.
  • Common causes: Same as P0770.
• P0772 – Shift Solenoid ‘E’ Stuck On
  • Common causes: Same as P0770.
• P0773 – Shift Solenoid ‘E’ Electrical
  • Common causes: Wiring or connector, faulty shift solenoid, TCM.
• P0774 – Shift Solenoid ‘E’ Intermittent
  • Common causes: Intermittent electrical connections, faulty solenoid, wiring.
• P0775 – Pressure Control Solenoid ‘B’ Malfunction
  • Common causes: Faulty solenoid, hydraulic problems, wiring or connector.
• P0776 – Pressure Control Solenoid ‘B’ Performance or Stuck Off
  • Performance issue or pressure control solenoid ‘B’ is stuck off.
  • Common causes: Same as P0775.
• P0777 – Pressure Control Solenoid ‘B’ Stuck On
  • Common causes: Same as P0775.
• P0778 – Pressure Control Solenoid ‘B’ Electrical
  • Common causes: Wiring or connector, faulty solenoid, TCM.
• P0779 – Pressure Control Solenoid ‘B’ Intermittent
  • Common causes: Intermittent electrical connections, faulty solenoid, wiring.

OBD / OBDII DTC P0780 – P0789

• P0780 – Shift Malfunction
  • General malfunction in the transmission shifting process.
  • causes: Internal transmission faults, faulty shift solenoids, transmission control module problems, mechanical within the transmission.
• P0781 – 1-2 Shift Malfunction
  • Common causes: Same as P0780, but specific to the 1-2 shift.
• P0782 – 2-3 Shift Malfunction
  • Common causes: Same as P0780, but specific to the 2-3 shift.
• P0783 – 3-4 Shift Malfunction
  • Common causes: Same as P0780, but specific to the 3-4 shift.
• P0784 – 4-5 Shift Malfunction
  • Common causes: Same as P0780, but specific to the 4-5 shift (in transmissions with at least 5 gears).
• P0785 – Shift/Timing Solenoid Malfunction
  • Common causes: Faulty shift/timing solenoid, wiring or connector, transmission control module.
• P0786 – Shift/Timing Solenoid Range/Performance
  • Common causes: Same as P0785.
• P0787 – Shift/Timing Solenoid Low
  • Common causes: Short to ground, faulty solenoid, wiring.
• P0788 – Shift/Timing Solenoid High
  • Common causes: Short to power, faulty solenoid, wiring.
• P0789 – Shift/Timing Solenoid Intermittent
  • Common causes: Intermittent electrical connections, faulty solenoid, wiring.

OBD / OBDII DTC P0790 – P0799

• P0790 – Normal/Performance Switch Circuit Malfunction
  • Common causes: Faulty switch, wiring or connector, transmission control module.
• P0791 – Intermediate Shaft Speed Sensor ‘A’ Circuit
  • Common causes: Faulty speed sensor, wiring or connector, transmission mechanical.
• P0792 – Intermediate Shaft Speed Sensor ‘A’ Circuit Range/Performance
  • Common causes: Same as P0791.
• P0793 – Intermediate Shaft Speed Sensor ‘A’ Circuit No Signal
  • Common causes: Faulty sensor, wiring or connector, transmission mechanical.
• P0794 – Intermediate Shaft Speed Sensor ‘A’ Circuit Intermittent
  • Common causes: Faulty sensor, intermittent electrical connections, wiring.
• P0795 – Pressure Control Solenoid ‘C’ Malfunction
  • Common causes: Faulty solenoid, hydraulic problems, wiring or connector.
• P0796 – Pressure Control Solenoid ‘C’ Performance or Stuck Off
  • Common causes: Same as P0795.
• P0797 – Pressure Control Solenoid ‘C’ Stuck On
  • Common causes: Same as P0795.
• P0798 – Pressure Control Solenoid ‘C’ Electrical
  • Common causes: Wiring or connector, faulty solenoid, transmission control module (TCM).
• P0799 – Pressure Control Solenoid ‘C’ Intermittent
  • causes: Intermittent electrical connections, faulty solenoid, wiring.

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.

Are These Codes Causing an Engine Light?

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.