🔥 Issue: Engine management, emission control, or drivetrain fault. Common: oxygen sensor (P0135), EGR valve (P0401), DPF pressure (P2453), mass airflow sensor (P0102), or loose fuel cap (P0455).

🚦 Symptoms: Rough idle, reduced power, increased fuel consumption, stalling, flashing = severe misfire (stop engine).

🔍 Diagnosis – multiple methods:

• OBD2 scan: Read codes, freeze frame, and mode $06 data. Compare with Mitsubishi-specific PIDs.
• Visual inspection: Vacuum hoses, intake leaks, damaged wiring near EGR.
• Live data: Monitor fuel trims (should be ±10%), O2 sensor switching, MAF g/s.
• Component activation: Use bidirectional control to test EGR, VGT solenoid.
• Smoke test: Pressurize intake to find hidden vacuum leaks.
• Compression test: If misfire code persists.

💰 Repair cost 2025: Diagnostic fee $120–200 | O2 sensor $280–500 | EGR valve $420–950 | DPF cleaning $700–1500 | Turbo actuator $800–2200

🛑 Issue: Low brake fluid (level sensor), worn pads (indicator), hydraulic leak, or parking brake switch stuck.

🚦 Symptoms: Soft pedal, squeal, pulling, or brake drag.

🔍 Diagnosis:

• Check fluid level in reservoir – if low, inspect for leaks at calipers, wheel cylinders, lines.
• Measure pad thickness through caliper opening (min 3mm).
• Pump pedal with engine off – should build pressure. If pedal sinks, master cylinder internal leak.
• Test parking brake switch (at pedal or lever).
• Check brake booster by pressing pedal while starting engine (pedal drops slightly).

💰 Repair cost: Brake fluid flush $90–150 | Front pads $180–400 | Caliper $250–550 | Master cylinder $350–800

⚡ Issue: Anti-lock system inactive – faulty wheel speed sensor, damaged tone ring, ABS pump relay, or module failure.

🚦 Symptoms: ABS light on, no ABS activation during hard braking, sometimes speedometer dead.

🔍 Diagnosis options:

• Scan ABS codes (C0035, C0040, C1233).
• Inspect tone ring for cracks, rust buildup, or missing teeth.
• Measure sensor resistance (typically 800–2000Ω) and AC voltage while spinning wheel.
• Check wiring harness near suspension, look for chafing or corrosion.
• Perform module self-test with diagnostic tool (some modules can be reset).

💰 Repair cost: Speed sensor $140–300 | Tone ring $100–250 | ABS pump $900–2000 | Module repair $500–1300

💥 Issue: Clockspring broken, seat belt pretensioner fault, front impact sensor, or low battery voltage causing historical code.

🚦 Symptoms: Airbag light stays on, horn may not work (clockspring).

🔍 Diagnosis:

• Use SRS-capable scanner (not all OBD2 read airbag codes).
• Inspect under steering wheel for broken ribbon (clockspring) – often code B1348.
• Check connectors under seats (yellow/orange) for looseness or corrosion.
• Measure squib resistance with special tool (never use multimeter directly on airbag).
• Clear codes and see if they return – some are from low battery jump-start.

💰 Repair cost: Clockspring $220–480 | Seat sensor $300–650 | Module reset $150–300 | Airbag module $900–1600

⛽ Issue: Low oil level, worn oil pump, clogged pickup, or faulty pressure switch.

🚦 Symptoms: Light flickers at idle, goes off when revving (if pump weak), tapping noise from valvetrain.

🔍 Diagnosis:

• Check dipstick level and oil condition (milky? metallic?).
• Install manual oil pressure gauge – compare with specs (min 10 psi per 1000 rpm).
• Remove oil filter and inspect for debris.
• Check pressure relief valve in oil pump.
• Listen for chain/bearing noise if pressure is truly low.

💰 Repair cost: Oil change $90–170 | Pressure switch $90–200 | Oil pump $900–1800 | Engine bearings $2500–5000

🌡️ Issue: Engine overheating – low coolant, thermostat stuck closed, radiator fan failure, water pump leak.

🚦 Symptoms: Needle in red, steam from hood, coolant smell, heater blows cold.

🔍 Diagnosis:

• Check coolant level in expansion tank (when cold).
• Verify electric fan operation (with AC on or at temp).
• Use infrared thermometer at thermostat housing – should open at ~88°C.
• Pressure test cooling system for leaks.
• Check for exhaust gases in coolant (head gasket failure).

💰 Repair cost: Coolant flush $120–200 | Thermostat $180–350 | Water pump $500–1000 | Radiator $600–1300

🌫️ Issue: Diesel particulate filter soot accumulation > limit, faulty differential pressure sensor, failed regeneration.

🚦 Symptoms: DPF light, reduced power, frequent regenerations, smell, engine oil dilution.

🔍 Diagnosis – multiple options:

• Read soot mass (ECU data) – typically >40g triggers light.
• Check differential pressure sensor voltage (key on engine off: ~0V).
• Monitor exhaust temps during regen (should exceed 550°C).
• Perform forced regeneration with professional scanner.
• Inspect for cracks or soot leaks around DPF can.
• Check oil level – if high, fuel dilution has occurred.

💰 Repair cost: Forced regen $250–450 | Pressure sensor $180–350 | DPF cleaning (chemical) $800–1400 | DPF replacement $2800–4800

⚡ Issue: One or more glow plugs failed, relay stuck, or control module fault.

🚦 Symptoms: Hard cold starting, white smoke on startup, glow plug light flashing or staying on.

🔍 Diagnosis:

• Measure resistance across each glow plug terminal to ground (0.5–2.0Ω).
• Check voltage at glow plug bus during preheat (battery voltage).
• Scan for glow plug DTCs (P0380, P0670).
• Observe glow lamp behavior – if it stays on too short, relay may be stuck.

💰 Repair cost: Glow plug (each) $60–180 | Relay $120–280 | Controller $400–950