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.
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HOMESERVICE MANUALSTOYOTA2004MATRIX XR, FWD, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 18 (ENGINE CONTROL SYSTEM SELF-DIAGNOSTICS)DIAGNOSTIC TESTSDTC P0450: EVAP PRESSURE SENSOR CIRCUIT, OR DTC P0451: EVAP PRESSURE SENSOR RANGE/PERFORMANCEDIAGNOSIS & REPAIR
2004 Toyota Matrix XR, FWD, Standard
Diagnosis & Repair
2004 Toyota Matrix XR, FWD, StandardSECTION Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
- Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Turn ignition on. Using voltmeter, check voltage between terminals No. 2 (Yellow/Red wire) and No. 18 (Brown wire) at ECM electrical connector E8. See Figure. This is the VC and E2 terminals on ECM. Voltage should be 4.5-5.5 volts. If voltage is within specification, go to next step. If voltage is not within specification, replace ECM.
- Turn ignition off. Connect voltmeter between terminals No. 18 (Brown wire) at ECM electrical connector E8 and No. 22 (Blue/Red wire) at ECM electrical connector E9. See Figure. This is the E2 and PTNK terminals on ECM. Remove fuel tank cap. Turn ignition on and note voltage. Voltage should be 3.0-3.6 volts. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM.
- Check for open and short in wiring harness and electrical connectors between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. Vapor pressure sensor is located on corner of fuel tank. See Figure. If wiring harness and electrical connectors are okay, replace vapor pressure sensor. See VAPOR PRESSURE SENSOR under EMISSION SYSTEMS & SUB-SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article. If wiring harness or electrical connector is defective, repair as necessary.
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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.