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Autopapyrus · Haval M6 1.5 Turbo 143 hp (2025)
https://autopapyrus.com/guides/haval/m6/engine-management-system-diagnostics/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Haval M6 1.5 Turbo 143 hp (2025): Engine Management System Diagnostics

The 1.5T (GW4G15) engine management system is built around the ECM, which reads the sensors and controls fuel delivery, ignition, boost pressure and valve timing. Diagnostics proceed in order: read the trouble codes, analyze the freeze frame, check live data, and physically inspect the suspect component. The manufacturer's exact step-by-step procedure for this model is not documented in publicly available service materials, so what follows is a general approach that applies to this engine.

Difficulty: Medium Time: 1-2 hours Steps: 13

Parts

10
№Part
01 Spark plugsif faulty
02 Ignition coilsif faulty
03 Manifold absolute pressure (MAP) sensorif faulty
04 Crankshaft position sensorif faulty
05 Camshaft position sensorif faulty
06 Knock sensorif faulty
07 Oxygen sensorif faulty
08 Boost control (wastegate) solenoid valveif faulty
09 PCV (crankcase ventilation) valveif faulty
10 Fuel injectorif faulty

Tools

5
  • OBD-II scanner with freeze frame and live data support (preferably one that supports Chinese vehicles)
  • multimeter
  • flashlight
  • socket and wrench set
  • smoke machine or pressure tester for checking the intake system (if available)

Step by step

13 steps
  1. Ask the owner about the symptoms, or recall them yourself: when the Check Engine light comes on, on a cold or warm engine, under what load, and whether there is hesitation, unstable idle, loss of power or increased fuel consumption. This narrows the search considerably.
  2. Inspect the engine bay. Check the oil and coolant levels, the condition and security of the boost hoses, whether there are oil leaks on the intercooler and hoses, whether the sensor connectors and wiring harnesses are intact, and whether there are signs of rodent damage.
  3. Check the battery: voltage with the engine off should be about 12.4-12.8 V, and with the engine running 13.8-14.6 V. Low voltage causes false communication and sensor codes.
  4. Connect the scanner to the OBD-II diagnostic port under the dashboard on the driver's side and turn the ignition on. Read all codes from all modules (engine, automatic transmission or CVT, ABS), not just the ECM. Note the status of each code: current, stored or pending.
  5. Save and study the freeze frame for each code: RPM, load, coolant temperature, boost pressure and fuel trims. It shows the conditions under which the fault occurred.
  6. Do not clear the codes right away. First record them, then clear them and see which ones return after a drive. Codes that return immediately indicate a permanent fault.
  7. Typical code groups and what to check. Misfires (P0300-P0304): spark plugs and ignition coils; swap a coil to another cylinder to see whether the code follows it. Lean or rich mixture (P0171, P0172): air leaks downstream of the MAF sensor and in the boost hoses, PCV valve, injectors, fuel pressure. Boost (P0234, P0299 and similar): tightness of the hoses and intercooler, wastegate actuator and solenoid valve. Camshaft/crankshaft position and timing (P0016 and similar): condition of the timing chain, the variable valve timing (VVT) solenoid, oil level and quality.
  8. View live data on a warmed-up engine: idle is usually around 650-800 rpm, coolant temperature reaches 90-100 °C, and short-term and long-term fuel trims should be within about ±10%. Trims that deviate strongly point to an air leak or a fuel problem.
  9. Check the spark plugs: remove them and evaluate the electrode color, the gap and carbon deposits. Tighten new plugs with a torque wrench to approximately 20-30 N·m (15-22 lb-ft) (verify the exact value against the manufacturer's specification). Apply a drop of anti-seize to the threads only if the manufacturer allows it; otherwise do not lubricate the threads.
  10. Test the suspect sensor with a multimeter: 5 V or 12 V supply at the connector, ground, and signal. Inspect the terminals for corrosion. Look up sensor resistance values and characteristics in the manufacturer's reference data rather than guessing.
  11. Check the intake and boost system for leaks: with the engine off, inspect the clamps and hoses, and if you have the equipment, use a smoke machine or a pressure test. Traces of oil on the intercooler point to turbocharger wear or a crankcase ventilation problem.
  12. Check the fuel and oil quality: low fuel or unsuitable oil leads to knock, misfires and timing codes. If you suspect bad gasoline, replace it and refuel with fuel of the octane rating required by the owner's manual.
  13. After the repair, clear the codes, warm up the engine, take a 15-20 minute test drive under varied loads, and read the memory again. Make sure the codes have not returned and the readiness monitors have set.

Common mistakes and warnings

  • Do not disconnect the battery terminals or handle connectors with the ignition on
  • Before removing any fuel system components, relieve the pressure in the fuel rail: on direct injection engines it is very high
  • If you cannot find the cause after the checks, or the codes relate to the ECM and require reflashing or coding, take the car to a dealer service center
  • A flashing Check Engine light means misfires, which destroy the catalytic converter, so do not drive the car