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.
Pinpoint Test C: Engine Emits Smoke
- Possible Sources
- Condensation build up in exhaust
- Air cleaner element
- Fuel injection system
- Coolant intrusion to combustion chamber
- Excessive engine oil consumption
- NOTE: Black soot near the exhaust tailpipe area is a normal condition created from rich air/fuel mixture under low load conditions.
- NOTE: The higher the ambient temperature, the less likely water vapor is seen exiting the tailpipe during engine startup and engine warm-up. The colder the ambient temperature, the more likely water vapor is seen exiting the exhaust tailpipe during engine startup and engine warm-up. This is a normal operating condition.
- NOTE: A sweet odor accompanying white smoke is not considered normal and is indicative of coolant in the exhaust.
- C1 CHECK FOR A NORMAL OPERATING CONDITIONNOTE: Make sure the engine is at ambient shop temperature prior to starting this test.NOTE: If a sweet odor accompanies white smoke, proceed to step C2.
- Start the engine while observing the exhaust exiting the tailpipe and allow the engine to reach normal operating temperature.
Is water vapor (white smoke) present and does the visible water vapor dissipate over time as the engine warms up to operating temperature?
Yes If blue or black smoke is not present, the vehicle is operating normally. If blue or black smoke is present, GO to C2 No GO to C2 - C2 CHECK FOR PCM (POWERTRAIN CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)
- Ignition ON.
- Carry out the PCMKOEO and KOER self-tests.
Are any Diagnostic Trouble Codes (DTCs) present?
Yes REFER to the Master DTC Chart to diagnose the DTC present. No For a white smoke concern, GO to Pinpoint Test B For a black smoke concern, GO to C3 For a blue or gray smoke concern, GO to Pinpoint Test A - C3 CHECK THE AIR CLEANER ELEMENT
- Check the air cleaner element.
Is the air cleaner element relatively clean and free of debris?
Yes GO to C4 No INSTALL a new air cleaner element. - C4 CHECK THE FUEL SYSTEM
- Check the fuel system for normal operation. REFER to the Diagnosis and Testing procedures in the appropriate Fuel and Charging Controls article for the engine being diagnosed. Refer to the appropriate Engine System article for the procedure.
Is the fuel system operating correctly?
Yes The concern is not currently present or the fuel system is not the cause of the concern. Verify the customer concern and the characteristics of the concern. No REPAIR as necessary.
NO RELATED
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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.