Issue: ECU detects emission, ignition, fuel, or sensor fault.

Symptoms: rough idle, power loss, increased fuel consumption, flashing = severe misfire.

Diagnosis (detailed): ① Read OBD2 codes (P codes). ② Check fuel cap. ③ Inspect vacuum hoses & MAF sensor. ④ For diesel: EGR valve, turbo actuator, boost pressure sensor. More options: smoke test for leaks, fuel pressure test, cylinder contribution test, compression test, exhaust backpressure test.

Repair cost: $120–$1,800 (diagnostic $100–$160, O2 sensor $250–$400, EGR $350–$700, catalytic converter $1,200–$2,500).

Issue: Low engine oil pressure (red light).

Symptoms: Ticking noise, hot engine, possible chime, light flickers at idle.

Diagnosis: ① Check oil level/dipstick. ② Inspect for leaks under van. ③ Test oil pressure with mechanical gauge (spec >10 psi at idle). ④ Inspect oil pump, pickup pipe (common on high mileage). More: check oil viscosity, pressure switch operation, examine oil filter for debris, perform oil analysis if metal particles.

Repair cost: $50 (top up) – $1,500 (oil pump) (switch $80–$150, pump $600–$1,200, labor $400–$800).

Issue: Charging system fault (alternator or battery).

Symptoms: Dim lights, slow crank, stall, “check charging” message, battery light on.

Diagnosis: ① Multimeter: battery 12.6V off, >13.8V running. ② Check alternator belt tension. ③ Inspect alternator connections & fusible link. ④ Load test battery. More: test voltage regulator, perform diode test, check for parasitic drain, scan for BMS (battery monitoring system) faults on smart charge versions.

Repair cost: $180–$900 (battery $150–$300, alternator $400–$800, BMS reset $100).

Issue: Engine overheating or low coolant level.

Symptoms: Steam from hood, heater blows cold, temp gauge high, red light.

Diagnosis: ① Check coolant reservoir level. ② Look for leaks (radiator, hoses, water pump). ③ Test thermostat operation (open at ~88°C). ④ Inspect radiator fan function. More: pressure test cooling system, check for combustion gas in coolant (head gasket test), inspect water pump weep hole, verify coolant sensor reading with scan tool.

Repair cost: $20 (coolant)–$1,500 (thermostat $200–$350, water pump $400–$800, radiator $500–$1,200, head gasket $1,500–$2,800).

Issue: Low brake fluid / parking brake on / EBD fault.

Symptoms: Spongy pedal, increased stopping distance, warning message.

Diagnosis: ① Check fluid level in reservoir. ② Inspect brake pads for wear. ③ Scan ABS module for codes. ④ Check for leaks at calipers/wheel cylinders. More: brake pressure test, master cylinder inspection, check brake booster vacuum, measure rotor thickness.

Repair cost: $100–$800 (fluid flush $100, pads $250, master cylinder $450, ABS module $600–$1,200).

Issue: Anti-lock brake system fault – normal brakes work.

Symptoms: ABS light on, traction control may disable, possible pulsing pedal.

Diagnosis: ① Scan ABS module (C1xxx codes). ② Inspect wheel speed sensors & tone rings. ③ Check wiring/connectors at each wheel. More: test sensor resistance (0.8–2.0 kΩ), use oscilloscope for signal pattern, check for corrosion, test pump motor relay.

Repair cost: $120–$600 (sensor $150–$300, module $500–$1,000, tone ring $200–$400).

Issue: Supplemental restraint system fault.

Symptoms: Light stays on, airbag may not deploy in crash.

Diagnosis: ① SRS scanner (special) read codes. ② Check connectors under seats. ③ Inspect clock spring. More: measure resistance on squib (requires care), check seat belt pretensioner continuity, verify occupant classification sensor (if equipped).

Repair cost: $150–$1,000 (clock spring $250–$400, module reset $200, seat sensor $300–$600).

Issue: Low tire pressure or sensor fault.

Symptoms: Light on, possibly pressure displayed low.

Diagnosis: ① Check all tire pressures with gauge. ② Inspect for punctures. ③ Use TPMS tool to trigger sensors. ④ Check battery in sensors. More: relearn procedure after rotation, check for aftermarket wheels interfering, test sensor with oscilloscope.

Repair cost: $10 (air)–$400 (sensor set) each sensor $60–$120, reprogramming $50–$100.

Issue: Diesel preheat system or plug failure.

Symptoms: Hard starting in cold, rough idle until warm, white smoke, light flashing.

Diagnosis: ① Test glow plug resistance (0.5–2 ohms). ② Check glow plug relay & fuse. ③ Monitor control module with scan tool. More: amperage draw test (each plug ~10-15A), check wiring harness for burns, test controller output voltage.

Repair cost: $100–$600 (set of 4 plugs $150–$300, relay $120, controller $350).

Issue: Diesel particulate filter clogged / regeneration required.

Symptoms: Reduced power, high idle, “exhaust filter full” message, increased fuel dilution.

Diagnosis: ① Check soot load with scanner. ② Perform forced regen (if allowed). ③ Inspect differential pressure sensor. More: check for oil dilution, injector balance, exhaust temperature sensor readings, check for turbocharger vane sticking (affects regen).

Repair cost: $300–$3,500 (cleaning $400–$800, new DPF $2,000–$3,500, pressure sensor $180–$300).

Issue: Electronic stability control / traction control disabled or fault.

Symptoms: Light on, system inactive, sometimes slip indicator.

Diagnosis: ① Scan ABS/ESP module. ② Check steering angle sensor calibration. ③ Inspect yaw sensor. More: brake switch adjustment, check wheel speed sensor correlation, test lateral acceleration sensor.

Repair cost: $100–$800 (sensor $200–$400, module $600–$1,200, calibration $150).

Issue: Low diesel exhaust fluid or quality issue.

Symptoms: Countdown warning, eventually power reduction, no-start after countdown zero.

Diagnosis: ① Refill DEF and check sensor. ② Test fluid concentration (refractometer). ③ Inspect DEF injector & pump. More: scan NOx sensor readings, check for DEF heater faults, examine DEF tank for crystallization.

Repair cost: $15 (refill)–$1,200 (pump/heater) (DEF injector $300–$600, NOx sensor $350–$700, tank heater $400–$800).

Issue: Electric or hydraulic power steering fault.

Symptoms: Heavy steering, warning light, loss of assist.

Diagnosis: ① Check power steering fluid level (if hydraulic). ② Scan for steering torque sensor codes. ③ Inspect wiring and connectors. More: check battery voltage (low voltage affects electric steering), test steering angle sensor, perform EPS module reset.

Repair cost: $150–$1,500 (fluid flush $100, sensor $300–$600, EPS motor $800–$1,500).

Issue: Automatic transmission overheating.

Symptoms: Slipping, harsh shifts, limp mode.

Diagnosis: ① Check fluid level & condition (burnt smell). ② Inspect cooler lines. ③ Verify cooler fan operation. More: check for towing overload, scan for TCM codes, measure line pressure.

Repair cost: $100–$3,000 (fluid/filter $250, cooler $400–$800, rebuild $2,500–$4,500).

Issue: Lane keeping, forward collision, or camera/radar fault.

Symptoms: Warning light, system unavailable, possibly no cruise control.

Diagnosis: ① Clean windshield area in front of camera. ② Check radar sensor behind front grille for blockage. ③ Scan for DTCs in ADAS module. More: check alignment (needs calibration after repairs), inspect wiring for damage.

Repair cost: $0 (cleaning) – $1,200 (camera calibration $400–$800, radar sensor $600–$1,200).