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 MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 139 (ENGINE CONTROL SYSTEM - SELF-DIAGNOSTICS)DIAGNOSTIC TESTSDTC P0136: HO2S 2 CIRCUITDIAGNOSTIC AIDS
1999 GMC Forward Control 5.7 R, Automatic
Diagnostic Aids
1999 GMC Forward Control 5.7 R, AutomaticSECTION Diagnostic Aids
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
Check for the following conditions:
- Check wiring harness for damage. If harness appears to be OK, observe HO2S 2 display on scan tool while moving connectors and wiring harnesses related to the sensor. A change in HO2S 2 display will indicate location of the fault.
- If a DTC P0136 is intermittent, driving vehicle under the conditions outlined in Inspection/Maintenance (I/M) procedures can verify whether the fault is present. See INSPECTION/MAINTENANCE HEATED OXYGEN SENSOR/OXYGEN SENSOR (HO2S/O2S) SYSTEM SET PROCEDURE under INSPECTION/MAINTENANCE PROCEDURES (DRIVE CYCLES).
- An intermittent malfunction may be caused by fault in the HO2S circuit sensor electrical circuit. Check the wiring harness and components for an intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article.
- Repair any electrical circuit faults found. The information included in freeze frame data can be useful in determining vehicle operating conditions when DTC first set.
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.
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.