MIL ON Due to Non Vehicle Related Faults
TSB No. TS 015 12125Section Title: General Tech. Info.
Division: Automotive
Category: Technical
SUBJECT:
ON-BOARD DIAGNOSTICS (OBD II)
MODEL:
ALL OBD II VEHICLES
CONDITION:
Non vehicle induced faults causing the "Check Engine", Malfunction Indicator Lamp (MIL) to turn ON leading to misdiagnosis, unnecessary repairs and customer dissatisfaction.
CAUSE:
Non vehicle induced faults, see text of this bulletin.
CORRECTION:
Dealer technicians should be aware of several non-vehicle faults that could trigger the MIL. Note: This list is not all inclusive.
FUEL RELATED FAULTS
The quality of the fuels has been a long concern of Suzuki and the others in the automotive industry. With the OBD II system, the possibilities of false triggering of the MIL due to the effects of fuel is greater.
Fuels are made to work with the general temperature conditions of the area where it is to be used. In short; if it is winter and the temperature is generally cold, the fuel is designed to vaporize easier. If it is summer and hot the fuel will be designed not to vaporize as easily.
Problems usually occur during the spring and fall months when temperature swings from day to day can vary greatly. For example; your customer may have winter formulated fuel in their gas tank, which will vaporize easily, on a warm spring day. This condition may cause a fuel trim DTC (diagnostic trouble code) due to excessive canister loading. On the other hand, should the customer be using summer formulated fuel (low vaporization qualities) on a cold fall day, it could cause hard starting and cold driveability which may trigger a misfire DTC.
Using fuels with the wrong octane rating for an OBD II equipped vehicle may cause driveability concerns. Consumers generally believe using "Premium" fuels will improve the performance of their vehicles. Premium fuels while having higher octane ratings may have less mid-range volatility which is required to turn fuel into a combustible vapor at low ambient temperatures. This may cause poor starting and cold driveability possibly triggering a misfire DTC.
Some fuels contain additives such as MMT which can affect various components of the vehicles emission system causing misfires or oxygen sensor DTC's.
If the vehicle runs out of or very low on fuel; a lean engine operation and misfire condition will cause a misfire DTC.
REFUELING
Some Suzuki vehicles are now equipped with enhanced evaporative emission control systems ("Evap II"). On these vehicles, an OBD II diagnostic checks the integrity of the entire evaporative emission system. If the customer looses or improperly secures the gas cap after refueling, the diagnostic system will detect the leakage of fuel vapors into the atmosphere and set a DTC.
ENVIRONMENT
Severe environmental conditions such as flooding may have an effect on the vehicle's ignition system. If the ignition system becomes wet, it may cause the engine to misfire and trigger a DTC.
VEHICLE HANDLING
Repeated cold starts without complete engine warm up can cause fouling of the spark plugs causing a misfire and setting of a DTC.
SEVERE VIBRATION
The misfire diagnostic system measures very small changes in the rotational speed of the crankshaft. Severe vibration in the driveline may have the same type of effect on the crankshaft rotational speed as a misfire and set a DTC.
POOR MAINTENANCE
OBD II diagnostics are very sensitive and will cause DTC's to set if the vehicle is not maintained according to the Suzuki maintenance schedule. Restricted air filters or fuel filters, worn spark plugs, and crankcase deposits from lack of oil changes are examples of maintenance-related components which can trigger DTC's.
NON-GENUINE SUZUKI PARTS
All of the OBD II diagnostics have been calibrated with genuine Suzuki parts. Modifications or installation of parts that do not match the calibrated values of the genuine Suzuki parts could possibly set DTC's. For example, installing a non-Suzuki muffler with either higher or lower flow rate than the original Suzuki muffler could cause the EGR system to operate incorrectly setting a DTC. Aftermarket electronics such as cell phones, stereos etc. may give off electromagnetic interference into the ECMs causing false sensor readings, emission devices to operate at the wrong time or not operate when they should and cause DTC's to set.