For 1990-2009 cars

### Excessive Exhaust Emissions or Odors -- L61

The vehicle fails an emission test or the vehicle has an excessive "rotten egg" smell. Excessive odors do not necessarily indicate excessive emissions.

#### L61

• | Check the faulty cooling system components (fan, thermostat, DTC sensors).

• | If the fuel system is running rich, the long term fuel trim is less than 70, refer to DTC P0172 and the diagnostic chart.

• | If fuel system is running lean, the long term fuel trim is more than 165, refer to DTC P0171 and the diagnostic chart.

• | If the emissions test indicates excessive NOX, check for items which cause the vehicle to run lean or too hot. Refer to the diagnostic chart and emission symptom chart.

• | If the emission test indicates excessive HC and CO or the exhaust has excessive odors, check for items which cause the vehicle to run rich. Refer to the diagnostic chart and emission symptoms chart and check for:

- | Incorrect fuel pressure

- | Fuel loading of EVAP canister

- | PCV system plugging or blocked PCV hose -- Check for fuel in the crankcase.

- | Three way catalytic converter lead contamination -- Check the exhaust backpressure and removal of the filler neck gas pump nozzle restrictor.

- | Improper fuel cap or damaged seal

- | EVAP vapor canister hose connections, condition, and routings -- Also, inspect the vehicle's hood and front of the dash seals for damage.

- | Faulty spark plugs, coil/module, converter, or ignition components for misfire

Important: Use of an emissions analyzer may help in locating points of fuel odor emissions. Even small amounts of fuel vapor will cause high levels of hydrocarbons to be indicated by the emissions analyzer. Slowly, move the analyzer probe near the suspect area. The hydrocarbon level will increase as the point of emissions is approached. The probe must be moved slowly, as it takes time for the gases to travel through the tester's hose.

Perform the Diagnostic Circuit Check.

Important: If the Emission Test shows excessive CO and HC, check the items which cause the car to run rich, the long term fuel trim is less than 70. Refer to Diagnostic Aids of DTC P0172 in this service manual.

Important: If the Emission Test shows excessive NOX, check the items which cause the car to run lean or too hot.

• | Check for vacuum leaks.

• | Check for lead contamination at the catalytic converter. Look for the removal of the fuel filler neck restrictor.

• | Check for carbon build-up. Remove the carbon with top engine cleaner. Follow the instructions on the can.

• | Check the PCV valve for being plugged or stuck or fuel in the crankcase.

• | Check the spark plugs and ignition components.

• | Check the engine coolant level.

• | Check the engine thermostat for a faulty part (always open) or for wrong heat range.

• | Check if the scan tool indicates a very high coolant temperature and the system is running lean.

Important: If the system is running RICH (fuel trim 70), refer to Diagnostic Aids of DTC P0172. If the system is running LEAN (fuel trim above 165) refer to Diagnostic Aids of DTC P0171 in this service manual.

• | Check for a properly installed fuel cap.

• | Check the fuel pressure.

• | Check the injector balance test.

• | Check the canister for fuel loading.