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.
1993 Volvo 850 AutomaticFACTORY OEM SERVICE PROCEDURE
Engine Controls - Tests W/Codes
- Introduction
- Self-Diagnostic System
- Self-Diagnostics
- Diagnostic Trouble Code Testing
- Fuel Injection Diagnosis
- Notes
- 1-1-2 (Fuel Injection ECU Fault)
- 2-1-2 (HO2S Signal Absent Or Faulty)
- 1-1-3 (HO2S Integrator At Maximum Enrichment Limit), 2-2-1 (Adaptive HO2S Control Rich At Part Load), 2-3-1 (Adaptive HO2S Control Lean At Part Load) & 5-1-2 (HO2S Integrator At Maximum Lean Running Limit)
- 1-2-1 (MAF Signal Absent Or Faulty)
- 1-2-3 (Engine Temperature Sensor Signal Absent Or Faulty)
- 2-2-3 (IAC Valve Signal Absent Or Faulty)
- 2-3-2 (Adaptive HO2S Control Provides Richer Mixture At Idle)
- 4-1-1 (Throttle Switch Signal Absent Or Faulty)
- 1-3-2 (Battery Voltage Too Low Or High)
- 1-3-1 (Ignition Speed System Signal Absent Or Faulty)
- 3-1-1 (Speedometer Signal Absent Or Faulty)
- 5-1-1 (Adaptive HO2S Control Provides Leaner Mixture At Idle)
- Ignition System Trouble Code Diagnosis
- 1-1-2 (ECU Fault)
- 1-2-3 (Engine Temperature Sensor Signal Absent Or Faulty)
- 1-3-1 (VSS Signal Absent) & 2-1-4 (VSS Signal Intermittent)
- 1-4-3 (Front Knock Sensor Signal Absent Or Faulty) & 4-3-3 (Rear Knock Sensor Signal Absent Or Faulty)
- 1-4-4 (Load Signal From Fuel Injection System Absent Or Faulty)
- 1-5-4 (EGR System Leakage)
- 2-4-1 (EGR Flow Incorrect)
- 3-1-1 (Speedometer Signal Absent Or Faulty)
- 3-1-4 & 3-2-4 (Camshaft Position Sensor Signal Absent Or Faulty)
- 4-1-1 (Throttle Switch Signal Absent Or Faulty)
- 4-1-3 (EGR Temperature Sensor Signal Incorrect/Missing)
- 4-3-2 & 5-1-3 (High Temperature Warning In ECU Box)
- Fuel Injection Diagnosis
- Summary
Factory Service Tools
Use the Manual With the Right Hardware
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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.
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