Holden Astra Problems

Based on your mechanic's diagnosis it would seem that the oxygen (02) sensor is probably faulty and needs replacing. There is no connection with the car's heater. If there is a problem with the heater it's different one.

It sounds like a very desirable car with its very low mileage, the extras, service history and the condition as described by you. It's one of those cars that you have to throw the valuation books out the window and go with your gut feeling. A 2002 Astra CD isn't worth a lot of money, but I would be asking $8000 to $10,000 for yours.

Our price guide puts the value of a 2001 Astra at between $1500 and $3500, which means you are trying to sell your car at the high end of the range. To achieve your price you would have to repair the air-conditioning, so it's worth spending the money. Air is an expected feature today and the value of a car with an air-con that's not working would be most unappealing. If you don't fix it I would put the value at around $1000-$1500.

I would think about $13,000 would be the value of it for insurance purposes.

The new Holden Cascada will be perfect for you. It's the spiritual successor to your Astra but a better drive and more classy. I'm sure that, like me, you'll give it The Tick

It would be wise to change the belt given that it’s five years since it was last changed. The consequences of it breaking are too dire to risk. Should it break it is most likely to result in extensive and expensive internal damage to the engine.

There should be no difference in the fuel if you sampled it at the fuel rail or the tank. The fuel at the rail is the fuel that is being delivered to the engine, and that's what matters most. You would appear to have a gripe with the dealer, and that appears to be what the Holden people are telling you, and should discuss your concerns with the dealer staff.

Putting Premium unleaded in it won't help. The problem is likely to be partially blocked fuel-injectors and I would suggest you have them cleaned.

It's always hard when you know there's a problem, but it's never present when there's a mechanic with you. It's hard to diagnose when you can't hear it for yourself, so keep notes on when it occurs and anything you observe that might give the mechanic a clue. Things like, does it do it on cold starts, under acceleration, slowing down, at idle. Even better, record it on your smart phone so you replay it for the mechanic the next time you take it in.