Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

SYS.OK|MANUAL.DB● LIVE

HOMESERVICE MANUALSSUBARU2002FORESTER BASEREPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROLS - SELF-DIAGNOSTICS - 2.5LDIAGNOSTIC TROUBLE CODE DEFINITIONS

2002 Subaru Forester Base

Diagnostic Trouble Code Definitions

2002 Subaru Forester BaseSECTION Diagnostic Trouble Code Definitions

DIAGNOSTIC TROUBLE CODE DEFINITIONS

Code No. ⁽¹⁾

Circuit Affected

P0031

Front Oxygen Sensor (A/F) Heater Circuit Low Input

P0032

Front Oxygen Sensor (A/F) Heater Circuit High Input

P0037 ⁽²⁾

Rear Heated Oxygen Sensor (HO2S) Heater Circuit Malfunction

P0037 ⁽³⁾

Rear Heated Oxygen Sensor (HO2S) Heater Circuit Low Input

P0038

Rear Heated Oxygen Sensor (HO2S) Heater Circuit High Input

P0065

Air Assist Injector Solenoid Valve Malfunction

P0066

Air Assist Injector Solenoid Valve Circuit Low Input

P0067

Air Assist Injector Solenoid Valve Circuit High Input

P0106

Pressure Sensor Circuit Range/Performance Problem (Low Input)

P0107

Pressure Sensor Circuit Low Input

P0108

Pressure Sensor Circuit High Input

P0111

Intake Air Temperature (IAT) Sensor Circuit Range/Performance Problem

P0112

Intake Air Temperature (IAT) Sensor Circuit Low Input

P0113

Intake Air Temperature (IAT) Sensor Circuit High Input

P0117

Engine Coolant Temperature (ECT) Sensor Circuit Low Input

P0118

Engine Coolant Temperature (ECT) Sensor Circuit High Input

P0121

Throttle Position (TP) Sensor Circuit Range/Performance Problem (High Input)

P0122

Throttle Position (TP) Sensor Circuit Low Input

P0123

Throttle Position (TP) Sensor Circuit High Input

P0125

Insufficient Coolant Temperature For Closed Loop Fuel Control

P0128

Thermostat Malfunction

P0130

Front Oxygen Sensor (A/F) Circuit Range/Performance Problem (Lean)

P0131

Front Oxygen Sensor (A/F) Circuit Malfunction (Open Circuit)

P0132

Front Oxygen Sensor (A/F) Circuit Malfunction (Short Circuit)

P0133

Front Oxygen Sensor (A/F) Circuit Slow Response

P0136 ⁽²⁾

Rear Heated Oxygen Sensor (HO2S) Circuit Malfunction

P0137 ⁽³⁾

Rear Heated Oxygen Sensor (HO2S) Circuit Low Input

P0138 ⁽³⁾

Rear Heated Oxygen Sensor (HO2S) Circuit High Input

P0139

Rear Heated Oxygen Sensor (HO2S) Circuit Slow Response

P0171

Fuel Trim Malfunction (A/F Too Lean)

P0172

Fuel Trim Malfunction (A/F Too Rich)

P0181

Fuel Temperature Sensor "A" Circuit Range/Performance Problem

P0182

Fuel Temperature Sensor "A" Circuit Low Input

P0183 ⁽²⁾

Fuel Temperature Sensor "A" Circuit High Input

P0183 ⁽³⁾

Fuel Temperature Sensor "A" Circuit High Input

P0301

Cylinder No. 1 Misfire Detected

P0302

Cylinder No. 2 Misfire Detected

P0303

Cylinder No. 3 Misfire Detected

P0304

Cylinder No. 4 Misfire Detected

P0327

Knock Sensor (KS) Circuit Low Input

P0328

Knock Sensor (KS) Circuit High Input

P0335

Crankshaft Position (CKP) Sensor Circuit Malfunction

P0336

Crankshaft Position (CKP) Sensor Circuit Range/Performance Problem

P0340

Camshaft Position (CMP) Sensor Circuit Malfunction

P0341

Camshaft Position (CMP) Sensor Circuit Range/Performance Problem

P0420 ⁽⁴⁾

Catalyst System Efficiency Below Threshold

P0420 ⁽⁵⁾

Catalyst System Efficiency Below Threshold

P0442

EVAP System Malfunction

P0444 ⁽²⁾

EVAP System Purge Control Valve Circuit Low Input

P0445 ⁽²⁾

EVAP System Purge Control Valve Circuit High Input

P0447

EVAP System Vent Control Circuit Low Input

P0448

EVAP System Vent Control Circuit High Input

P0451

EVAP System Pressure Sensor Range/Performance Problem

P0452 ⁽²⁾

EVAP System Pressure Sensor Low Input

P0452 ⁽³⁾

EVAP System Pressure Sensor Low Input

P0453 ⁽²⁾

EVAP System Pressure Sensor High Input

P0453 ⁽³⁾

EVAP System Pressure Sensor High Input

P0456

EVAP System Malfunction

P0457 ⁽³⁾

EVAP System Malfunction

P0458 ⁽³⁾

EVAP System Purge Control Valve Circuit Low Input

P0459 ⁽³⁾

EVAP System Purge Control Solenoid Valve Circuit High Input

P0461 ⁽²⁾

Fuel Level Sensor Circuit Range/Performance Problem

P0462 ⁽²⁾

Fuel Level Sensor Circuit Low Input

P0462 ⁽³⁾

Fuel Level Sensor Circuit Low Input

P0463 ⁽²⁾

Fuel Level Sensor Circuit High Input

P0463 ⁽³⁾

Fuel Level Sensor Circuit High Input

P0464 ⁽²⁾

Fuel Level Sensor Circuit Intermittent Input

P0464 ⁽³⁾

Fuel Level Sensor Circuit Intermittent Input

P0480 ⁽²⁾

Cooling Fan Relay No. 1 Circuit Low Input

P0483

Cooling Fan Function Problem

P0500 ⁽²⁾

Vehicle Speed Sensor (VSS) Malfunction

P0500 ⁽³⁾

Vehicle Speed Sensor (VSS) Malfunction

P0506

Idle Control System RPM Lower Than Expected

P0507

Idle Control System RPM Higher Than Expected

P0512

Starter Switch Circuit High Input

P0604

Internal Control Module Memory Check Sum Error

P0691 ⁽³⁾

Cooling Fan Relay No. 1 Circuit Low Input

P0692 ⁽³⁾

Cooling Fan Relay No. 1 Circuit High Input

P0703

Brake Switch Input Malfunction (A/T)

P0705 ⁽⁶⁾

Transmission Range Sensor Circuit Malfunction (A/T)

P0710 ⁽⁶⁾

Transmission Fluid Temperature Sensor Circuit Malfunction (A/T)

P0715 ⁽⁶⁾

Torque Converter Turbine Speed Sensor Circuit Malfunction (A/T)

P0720 ⁽⁶⁾⁽⁷⁾

Output Speed Sensor (Front VSS) Circuit Malfunction (A/T)

P0720 ⁽⁶⁾⁽⁸⁾

Output Speed Sensor (VSS No. 2) Circuit Malfunction (A/T)

P0725 ⁽⁶⁾

Engine Speed Input Circuit Malfunction (A/T)

P0731

Gear 1 Incorrect Ratio (A/T)

P0732

Gear 2 Incorrect Ratio (A/T)

P0733

Gear 3 Incorrect Ratio (A/T)

P0734

Gear 4 Incorrect Ratio (A/T)

P0741

Torque Converter Clutch System Malfunction (A/T)

P0743 ⁽⁶⁾

Torque Converter Clutch System (Lock-Up Duty Solenoid) Electrical (A/T)

P0748 ⁽⁶⁾

Pressure Control Solenoid (Line Pressure Duty Solenoid) Electrical (A/T)

P0753 ⁽⁶⁾

Shift Solenoid "A" (No. 1) Electrical (A/T)

P0758 ⁽⁶⁾

Shift Solenoid "B" (No. 2) Electrical (A/T)

P0778 ⁽⁶⁾

2-4 Brake Pressure Control Solenoid Valve Circuit Malfunction (A/T)

P0785 ⁽⁶⁾

2-4 Brake Timing Control Solenoid Valve Circuit Malfunction (A/T)

P0851 ⁽³⁾

Inhibitor Switch Circuit Low Input (A/T)

P0851 ⁽³⁾

Neutral Position Switch Circuit Low Input (M/T)

P0852 ⁽³⁾

Inhibitor Switch Circuit High Input (A/T)

P0852 ⁽³⁾

Neutral Position Switch Circuit High Input (M/T)

P0864 ⁽³⁾

A/T Diagnosis Input Signal Circuit Malfunction

P0865 ⁽³⁾

A/T Diagnosis Input Signal Circuit Low Input

P0866 ⁽³⁾

A/T Diagnosis Input Signal Circuit High Input

P1110 ⁽²⁾

Atmospheric Pressure Sensor Circuit Low Input

P1110 ⁽³⁾

Atmospheric Pressure Sensor Circuit Low Input

P1111 ⁽²⁾

Atmospheric Pressure Sensor Circuit High Input

P1111 ⁽³⁾

Atmospheric Pressure Sensor Circuit High Input

P1112 ⁽²⁾

Atmospheric Pressure Sensor Circuit Range/Performance Problem

P1112 ⁽³⁾

Atmospheric Pressure Sensor Circuit Range/Performance Problem

P1137

Front Oxygen Sensor (A/F) Circuit Range/Performance Problem

P1142

Throttle Position (TP) Sensor Circuit Range/Performance Problem (Low Input)

P1146

Pressure Sensor Circuit Range/Performance Problem (High Input)

P1400

Fuel Tank Pressure Control Solenoid Valve Circuit Low Input

P1420

Fuel Tank Pressure Control Solenoid Valve Circuit High Input

P1442

Fuel Level Sensor Circuit Range/Performance Problem 2

P1443

EVAP System Vent Control Function Problem

P1446 ⁽³⁾

EVAP System Atmospheric Pressure Solenoid Valve Circuit Low Input

P1447 ⁽³⁾

EVAP System Atmospheric Pressure Solenoid Valve Circuit High Input

P1448 ⁽³⁾

EVAP System Atmospheric Pressure Solenoid Valve Circuit Range/Performance Problem

P1480 ⁽²⁾

Cooling Fan Relay No. 1 Circuit High Input

P1507

Idle Control System Malfunction (Fail-Safe)

P1510

Idle Air Control (IAC) Solenoid Valve Signal No. 1 Circuit Low Input

P1511

Idle Air Control (IAC) Solenoid Valve Signal No. 1 Circuit High Input

P1512

Idle Air Control (IAC) Solenoid Valve Signal No. 2 Circuit Low Input

P1513

Idle Air Control (IAC) Solenoid Valve Signal No. 2 Circuit High Input

P1514

Idle Air Control (IAC) Solenoid Valve Signal No. 3 Circuit Low Input

P1515

Idle Air Control (IAC) Solenoid Valve Signal No. 3 Circuit High Input

P1516

Idle Air Control (IAC) Solenoid Valve Signal No. 4 Circuit Low Input

P1517

Idle Air Control (IAC) Solenoid Valve Signal No. 4 Circuit High Input

P1518

Starter Switch Circuit Low Input

P1540

Vehicle Speed Sensor (VSS) Malfunction 2

P1560

Back-Up Voltage Circuit Malfunction

P1590 ⁽²⁾

Inhibitor Switch Circuit High Input (A/T)

P1591 ⁽²⁾

Inhibitor Switch Circuit Low Input (A/T)

P1592 ⁽²⁾

Neutral Position Switch Circuit Malfunction (M/T)

P1594 ⁽²⁾

A/T Diagnosis Input Signal Circuit Malfunction

P1595 ⁽²⁾

A/T Diagnosis Input Signal Circuit Low Input

P1596 ⁽²⁾

A/T Diagnosis Input Signal Circuit High Input

P1698

Engine Torque Control Cut Signal Circuit Low Input (A/T)

P1699

Engine Torque Control Cut Signal Circuit High Input (A/T)

P1700 ⁽⁶⁾

Throttle Position (TP) Sensor Circuit Malfunction (A/T)

P1701

Cruise Control Set Signal Circuit Malfunction (A/T)

P1703 ⁽⁶⁾

Low Clutch Timing Control Solenoid Valve Circuit Malfunction (A/T)

P1711

Engine Torque Control Signal No. 1 Circuit Malfunction (A/T)

P1712

Engine Torque Control Signal No. 2 Circuit Malfunction (A/T)

⁽¹⁾	DTC applies to all models unless otherwise specified.

⁽²⁾	Forester, Impreza and Outback Sport.

⁽³⁾	Legacy and Outback.

⁽⁴⁾

Forester.

⁽⁵⁾	Impreza, Outback Sport, Legacy and Outback.

⁽⁶⁾	Covered in entirety in appropriate DIAGNOSTICS article in AUTOMATIC TRANSMISSIONS in TRANSAXLE/TRANSMISSION.

⁽⁷⁾	Impreza and Outback Sport.

⁽⁸⁾	Forester, Legacy and Outback.

RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

Shop Manual-Ready Tools Free Quote Check Quote Shield Pro

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.