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The Used Car Dealers Association of Ontario

416-231-2600 or 1-800-268-2598 or fax 416-232-0775

Used Car Dealers Association of Ontario   

Drive Clean Best Practices for Used Car Dealers

Used car dealers in Southern Ontario have been familiar with Drive Clean for over a decade. All used vehicles require a Drive Clean Pass report before the new owner can obtain licence plates. This ensures that the purchased vehicle is free from emissions defects.

It’s the Law

The Environmental Protection Act prohibits the seller from providing a vehicle with faulty emissions controls to an unwary buyer.

What is new with Drive Clean?

Beginning January 1, 2013, there will be a new emissions inspection procedure for most cars, vans, SUVs and light trucks. Ontario will be joining the other North American emissions inspection programs by requiring vehicles to be inspected with the on-board diagnostics test procedure.

OBD stands for On-Board Diagnostics II

Model year 1998 and newer cars, vans, SUVs and light trucks, are equipped with on-board diagnostics (OBD) computers that constantly check the emissions control systems to ensure they are working properly. The OBD system detects problems well before symptoms such as poor performance, high emissions or poor fuel economy are recognized by the driver.

The OBD system monitors emissions controls every time a vehicle is operated and even when it is parked. The old dynamometer and tailpipe test measured emissions only at a particular speed, load and moment in time.

Quick E-Check for Trade-in and Auctioned Vehicles

Before accepting a vehicle for resale - do a quick emissions check. Plug a portable scan tool into the vehicle’s Diagnostic Link

Connector (DLC) to download all DTCs and check for Readiness:

A vehicle that reports no Diagnostic Trouble Codes (DTC) and all supported monitors are “Ready” will mostly likely pass its Drive Clean inspection.

If DTCs are found or one or more monitors are “Not Ready” the vehicle will require repairs before it can be fit for resale.


The new Drive Clean OBD Emissions Inspection

The new Drive Clean emissions test for OBD equipped vehicles will ask for emissions control system results directly from the vehicle’s OBD computer.

Only older, pre-OBD, vehicles will receive a tailpipe exhaust gas inspection.

Pre-OBD passenger cars and light trucks (1988-1997) will be tested for tailpipe emissions by the Two Speed Idle (gasoline) or visual smoke (diesel) tests.

Heavy SUVs and pickup trucks (1988-2006) with GVWRs greater

than 3856 kg are pre-OBD vehicles.

Heavy SUVs and pickup trucks (2007 and newer) with GVWR 3856 kg to 4,500 kg are OBD capable vehicles and will be tested by OBD.

Malfunction Indicator Light (MIL)

When an emissions problem is detected on an OBD equipped vehicle, an instrument panel warning light called a Malfunction Indicator Light (MIL) turns on to alert the driver. On some vehicles it will appear as a yellow engine symbol, CHECK ENGINE or SERVICE ENGINE SOON alert. Most vehicles use the following symbols to represent the MIL:

The purpose of the MIL is to warn the driver of an emissions related problem that needs to be repaired. During normal operation, the MIL will turn on for a few seconds when the engine is first started and turn off when the engine is running. If the MIL remains on, the OBD system is warning the driver that it has detected an emissions control system problem.

The OBD system will automatically turn off the MIL if the issue(s) that caused the problem are no longer detected. This will happen when the OBD system checks a component or system three consecutive times and no longer detects the initial problem.

For example, if a gas cap was not properly tightened after refuelling, the OBD system detects an evaporative leak and turns on the MIL. Once the gas cap is


tightened, the OBD system will recognize this and the MIL will be turned off after a few days of normal driving.

If the Malfunction Indicator Light (MIL) is on during the Drive Clean emissions test, the result will likely be a FAIL.

A vehicle with a MIL on has an emissions control system problem. It must be repaired before it can successfully pass a

Drive Clean retest.

Systems Monitored and Status

The Drive Clean test Vehicle Inspection Report (VIR) includes a table of the

Systems Monitored and their Status. A vehicle’s OBD computer checks emissions systems performance by monitoring data from the engine, transmission, fuel system, and emissions controls. Up to eleven (11) monitors

(software routines) check these major systems and components under specific operating conditions.

There are three (3) “continuous” monitors found in every gasoline powered OBD vehicle: misfire, fuel trim, and comprehensive components. “Continuous” monitors are constantly being checked and evaluated by the vehicle’s OBD computer while the vehicle is running. Conversely, the other eight (8) “non- continuous” monitors need specific operating conditions to occur before checks can be completed.

The exact number of monitors in any vehicle depends on the manufacturer’s emissions control strategy. No vehicle has all 11 monitors present, so the “status” or condition of some monitors will be “Unsupported”. For all of a vehicle’s supported monitors, the “status” will be “Ready” or “Not Ready”.

Ready or Not

A monitor is considered “Ready” when it successfully completes a check. If a monitor has not or cannot complete its check it will report “Not Ready”.

Monitors that have completed their checks typically stay “Ready” and do not become “Not Ready” on their own.

The three (3) “continuous” monitors become “Ready” when a vehicle is running.

The eight (8) “non-continuous” monitors need specific operating conditions before they can become “Ready”.


How does a Vehicle become Not Ready?

A vehicle’s OBD computer memory can be cleared and all monitors set to “Not

Ready” when:

oCars sit on the lot for extended periods of time with the battery discharged or disconnected,

o Engine repairs or maintenance temporarily interrupts battery power,

oWeak batteries, that can barely start an engine, will have voltage drops during cranking. The temporary voltage sag can also prevent an emissions inspection from completing – causing it to be rejected.

Disconnecting the battery, a dead or weak battery, badly corroded connections, an electrical problem that causes a low voltage condition, or clearing the OBD computer codes prior to an emission test will result in an emissions test failure for


So how do you get a vehicle “Ready”?

After power is restored, the vehicle needs to be driven under various conditions (drive cycles), to allow the OBD computer to check emissions systems and report each monitor “Ready” for an emissions test.

A vehicle can be difficult or impossible to get “Ready” when it has an emissions control system problem and may require repairs to get ready. If enough monitors are “Not Ready” (have not completed their checks), the vehicle will fail its Drive Clean emissions test.

A few days of combined city and highway driving, will normally allow the OBD monitors to run and become “Ready”. Most vehicles with no emissions control system problems can become “Ready” within minutes of normal driving.

Vehicles with emissions control system issues will take longer to become “Ready”. Once “Ready”, there may be an emissions problem that turns the MIL on and fails the Drive Clean emissions test. Here is a ‘generic drive cycle’ that should allow most vehicles’ OBD system to become “Ready”:

Step 1: Make sure the vehicle has been parked for eight hours without a start.

Step 2: Start the engine and let it idle in Drive for two-and-a-half minutes with the Air Conditioning (A/C) and rear defroster on.

Step 3: Turn the A/C and rear defroster off. Drive the vehicle for 10 minutes at highway speeds.


Step 4: Drive the vehicle for 20 minutes in stop-and-go traffic. Step 5: The drive cycle is complete.

For the ‘generic drive cycle’ to work the gas tank should be ¼ to ¾ full and the vehicle must be driven smoothly and avoid rapid acceleration

Readiness Tips

Check the thermostat operation (e.g. stuck open), fuses, battery connections and wiring to the on-board computer.

Inefficient aftermarket catalytic converters may not allow the catalyst monitor to become “Ready”.

Check Technical Service Bulletins (TSB) for OBD computer problems that can be fixed by a PCM reflash.

Use an “automotive memory saver” when replacing or disconnecting a battery during service to retain the OBD information rather than erasing it. These tools are relatively cheap and can be found at almost any automotive parts suppliers outlets.

So How do you Keep a Vehicle Ready?

A vehicle with all its monitors “Ready” can stay “Ready” while sitting on your lot, by keeping the on board computers energized. To prevent the memory from being erased take the following precautions:

o Ensure car batteries are never discharged below or disconnected, o Regularly charge batteries – especially in winter,

oLoad test and replace weak batteries. The voltage sag during cranking may clear the monitors or prevent an emissions inspection from completing – causing it to be rejected,

o Do not clear codes when performing maintenance on a vehicle, and,

oWhen replacing or disconnecting a car battery, use an automotive “Memory Saver” device plugged into the Diagnostic Link Connector


Diagnostic Trouble Codes (DTC)

When a vehicle’s OBD system detects an emissions related malfunction, a

Diagnostic Trouble Code (DTC) is stored in the on-board computer and the

Malfunction Indicator Lamp (MIL) on the instrument panel lights up. There is something wrong with the vehicle’s emissions control system and it needs to be repaired.


The Vehicle Inspection Report (VIR) is not a diagnostic analysis. The DTC on the VIR indicates the general area of the emissions failure and will help a repair technician determine the appropriate repairs. The DTC does not provide the motorist or the repair technician with everything needed to repair the malfunction.

Aimlessly replacing parts in an attempt to remove a DTC is ineffective and potentially expensive. For example, an O2 sensor related DTC could be the result of an exhaust leak upstream of the O2 sensor. In this case, replacing a properly functioning O2 sensor will not fix this problem.

A good repair technician will follow the vehicle manufacturer’s recommended diagnostic practices and procedures to determine and repair the specific source of the DTC problem.

A transmission problem can be directly related to the emissions control system and can turn the MIL on.

Transmission malfunctions can prevent a vehicle from running efficiently, increasing emissions above OBD standards.


All OBD equipped vehicles have a standardized Diagnostic Link Connector (DLC) that the Ontario Test Unit (OTU) uses to obtain OBD data.

Failure to Communicate

If the vehicle’s OBD systems cannot provide data to the OTU, the emissions test result will be a Fail for communication.

Two of the most common causes of communication failures are damaged DLCs or improper wiring for an aftermarket installed device like a CD player, satellite radio, navigation system or security system. Ensure the aftermarket device is not attached to, interfering with or drawing power from the DLC, or otherwise affecting the vehicle’s computer or electrical system.

Drive Clean Inspectors will reject a vehicle from testing if there is anything attached to the DLC or if the DLC appears to have been tampered with.