Camry's sensor indicates evaporative emissions fault

Q: I have a 2001 Toyota Camry four-cylinder, with approximately 150,000 km on it.

The Check Engine light is on, and two mechanics have said that it is a sensor at the fuel tank – that this is hard to fix and not to fix it. The car is running well.

Technician Tom Zekveld replies:

Your mechanics have likely found that the Check Engine light is on due to an "Evaporative Emission System" failure.

Sensors located in the fuel tank area are usually related to the evaporative emissions. When an "Evaporative" Code is set, there is a system fault, indicating either a faulty sensor, solenoid, or a leak in the system.

The Evaporative Emission system is unique in the fact that an evaporative failure generally does not affect tailpipe emissions or vehicle driveability. Therefore the vehicle continues to run well, despite the engine light on your dash.

But the Check Engine light is the only way your vehicle tells you that it has a system problem. So if the light is on permanently due to an evaporative emissions failure, how will you be warned when another, possibly more serious, failure occurs?

A 2001 Camry with 150,000 km on it should be good for many more years and kilometres. My advice is that you fix the evaporative problem so you can drive with peace of mind – not to mention the possibility of reducing evaporative emissions into the atmosphere, the air that you and I share.

Q: I own a 2005 Mustang GT, which I bought new. If I don't drive the car for 10 days, the battery is totally discharged. I had to call CAA three times in the last half-year. They checked the battery and the alternator, and concluded that everything was in order.

Last week I took the car to Ford, since I have extended warranty. I was told that they can't find anything wrong and advised me to disconnect the negative cable from the battery when I am not driving it.

Technician Tony Prochilo replies:

All of today's vehicles contain microprocessors that draw small amounts of electrical current even when you shut the vehicle off.

This draw is often referred to as a "parasitic" draw. Ford says that the normal parasitic draw for your car (with the key off) is between 20 to 30 milliamps.

All automotive batteries regardless of make or model will self-discharge while in storage or simply parked for a few days. However, if a device, whether a microprocessor or a simple glovebox lamp, is not electrically shutting off after the vehicle has been parked, it will discharge the battery to a level that would make it difficult to start.

I would have a repair facility measure the parasitic draw with the key turned off and all the doors closed. If it exceeds the specified draw, they will have to systematically disconnect each electrical circuit to isolate the area of concern. It could be as simple as a defective switch not shutting off a light bulb.

Email your mechanical questions to wheels@thestar.ca.

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