Excessive Exhaust Emissions Or Odors: Notes

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

• Check:
  • Faulty cooling system components (fan, thermostat, ECM1 sensors).
• If fuel system is running rich (long term fuel trim less than 118):
  • Rich fuel system, refer to DTC P0172, P0175 in SELF-DIAGNOSTICS - 3.0L .
• If fuel system is running lean (long term fuel trim more than 138):
  • Lean fuel system, refer to DTC P0171 and P0174 in SELF-DIAGNOSTICS - 3.0L .
• If emissions test indicates excessive NOX, check for items which cause vehicle to run lean or too hot. Refer to SELF-DIAGNOSTICS - 3.0L or TROUBLE SHOOTING - NO CODES .
• If emission test indicates excessive HC and CO or exhaust has excessive odors, check for items which cause vehicle to run rich. Refer to diagnostic chart in SELF-DIAGNOSTICS - 3.0L or TROUBLE SHOOTING - NO CODES and check for:
  • Incorrect fuel pressure.
  • Fuel loading of EVAP canister.
  • Three way catalytic converter lead contamination. Check exhaust backpressure, and check for removal of 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 dash seals for damage.
  • Faulty spark plugs, coil/module, converter, ignition components or 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.