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With fall here and winter approaching car heating problems can become just as important as air conditioning in the summer months.

No driver wants to freeze or burn while they're driving their car down the road.
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heater control valve
The heater control valve is one of the many components that are responsible for warming the interior compartment. This valve allows hot coolant to be piped directly from the engine to the heater core.

The heater core then transfers the heat to the interior compartment by recirculating air from inside the car across the heater core fins.

This continued cycle of heating the air inside the vehicle is extremely efficient.

Heater control problems

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climate control
Many things can cause low output from your car's heater. Understanding how to heater control valve works can be important in diagnosis of this car problem. The heater valve sometimes called the water flow valve controls the direction and amount of coolant flow to the core.

In the closed position to heater control valve allows no hot coolant to enter the heater core. In the open position the part allows engine heated coolant to circulate through the firewall mounted core.

Consult your online auto service manual for specific locations on your vehicle.
 
 
The park brake interlock is a safety system that stops you from putting the vehicle in gear unless the brake pedal is depressed. But what if you put your foot on the brake and it does not come out of park?
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Interlock Solenoid
Not only have I received a lot of questions about this common shifter problem I have also seen it on the vehicles that I work on locally. Since the mid 90's all vehicles now come equipped with a park brake interlock system.

This is a great safety feature that requires you to have your foot on the brake pedal before it will allow you to shift from the park position to your desired gear. This system operates by a switch on the brake pedal that intern operates a interlock solenoid on the shifter mechanism.

When you apply the brake the solenoid pulls the shifter lock out of the way to allow free shifter movement. Some vehicles are equipped with a cable that is activated by a solenoid mounted on the brake pedal. Either system will release the safety lock on the shifter that allows you to move it from the park position.
 
 
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Check Engine
The oxygen sensor is often suspected when the check engine light comes on. The O2 is one of the most commonly replaced sensors.

It is also one of the most misdiagnosed, electrical emissions components. Since this sometimes-expensive car part is a non-re-terminable item at most part stores, it is a good idea to confirm diagnosis before replacement.

And often during my diagnostic procedure I will uncover the cause of the check engine light problem that is less expensive then a replacement o2.
Add to the above facts that most cars have 4 of these exhaust stream sensors and you really want to make sure you are only replacing failed components.

To follow is a run down on how to diagnose check engine light codes in the PO171-PO175 range, which are your most common o2 codes.

How to Diagnose oxygen sensors

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Cheap Scanner
To effectively diagnose failed oxygen sensors you need to see the operating voltages. A scan tool is the easiest way to do this but an automotive meter can also be used. Diy scan tools that can read data streams can be had for under $200

The data stream voltage for the O2 should vary quickly from about 200 to 800 mV. A good rule of thumb is that the voltage should vary above and below the half way mark of 500 milivolts in a steady even pattern.

If you have sensors with a fixed voltage or a voltage that is always below 500, then you want to check the wiring to the sensor.