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 MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 4 (ENGINE CONTROLS - SELF-DIAGNOSTICS - 4.3L)DIAGNOSTIC TESTSDTC P0125: EXCESSIVE TIME TO ENTER CLOSED LOOP FUEL CONTROLDIAGNOSTIC PROCEDURES
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8
Diagnostic Procedures
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Diagnostic Procedures
WARNING: This page is about a different variant/trim than selected.
- Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM. After performing powertrain diagnostic system check, go to next step.
- If cooling system is low on coolant, repair as necessary. After repairs, go to step 10. If cooling system is not low on coolant, go to next step.
- Turn ignition off. Disconnect ECT sensor. ECT sensor is located on the side of left cylinder head. Connect a fused jumper wire (3-amp) between ECT sensor connector terminals. Turn ignition on, engine off. Using scan tool, observe ECT sensor temperature. If scan tool indicates ECT sensor temperature is more than 280°F (138°C), go to step 7. If scan tool does not indicate ECT sensor temperature is more than 280°F (138°C), go to next step.
- Turn ignition off. Connect a fused jumper wire (3-amp) between ECT sensor connector terminal "B" (Yellow wire) and ground. Turn ignition on, engine off. Using scan tool, observe ECT sensor temperature. If scan tool indicates ECT sensor temperature is more than 280°F (138°C), go to next step. If scan tool does not indicate ECT sensor temperature is more than 280°F (138°C), go to step 6.
- Repair high resistance or open in Gray wire ("C" & "K" series) or Black wire ("G" series) between ECT sensor and PCM. After repairs, go to step 10.
- Repair high resistance or open in Yellow wire between ECT sensor and PCM. After repairs, go to step 10.
- Remove ECT sensor. Suspend ECT sensor and a thermometer in a pan of water. Place pan on a burner or hot plate. Check resistance of ECT sensor through 50-194°F (10-90°C). See appropriate SENSOR OPERATING RANGE CHARTS article. If resistance and temperature closely match, go to next step. If resistance and temperature do not closely match, go to step 9.
- Reinstall ECT sensor. Diagnose and repair thermostat. After repairs, go to step 10.
- Replace ECT sensor. After repairs, go to next step.
- Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria. If DTC runs and passes, go to next step. If DTC does not run and pass, go to step 2.
- Using scan tool, observe stored information. If scan tool displays any DTCs that have not been diagnosed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool does not display any DTCs, system is okay.
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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.