Arriell Perry

I purchased a 2006 Equinox from a private party. The car was listed as $1900, but we agreed on $1700. Because the car didn't have plates, I couldn't take it for a full test. The check engine light was on, and the code came up as P0171. I've spent $850 in repairs so far. They have replaced the O2 sensor, repaired the vacuum leak, reset the computer, and replaced the catalytic converter. That converter code came up after the vacuum leak was repaired. Now, my car is making this gurgling sound everytime I turn the wheel to the left while pressing on the gas. The reduced engine power light has been coming on every since the catalytic converter has been replaced. Today, I've had to pull over, turn my car off, wait 10 seconds, and turn it back on at least 15 times. Aslo, there's smoke coming from the air vents that smell like coolant. I need help.

ASE Doc

Reduced Engine Power message is displayed when there is an issue with electronic throttle control. You may have an issue with either the throttle body, the accelerator pedal position sensor, PCM or wiring. It can also just be a dirty sticking throttle. Remove the inlet hose from the throttle body and inspect for black dirty build up around the throttle. Clean it using Throttle Body Cleaner and a rag. A nylon bristle bore brush also helps to remove the hardened dirt ring. Do Not Spray the cleaner into the throttle opening either with the engine running or off. This will not effectively remove the build up and can damage the catalyst or risk hydrolocking the engine. After cleaning, start the engine and let it clear out the material that gets into the intake. Then, turn the engine off, wait 20 seconds, turn the key to run, leave it for 20 seconds, back to off for 20 seconds, then on for 20 seconds before starting the motor. This process lets the PCM relearn minimum throttle.

It sounds like you may have a leaking heater core. The previous owner probably neglected cooling system maintenance and the core has failed. Heater core replacement requires removal of the dash and to do it right requires removal of the HVAC housing for disassembly, though it can be done in the car. I do not recommend stop leak for heater core leaks. But, if you wish to try it, that's on you.

I am a professional automotive technician. In fact I am a 40 year veteran ASE Master Technician and for the past 29 years, a diagnostic specialist. Guessing at diagnostic problems makes me cringe a little. Unfortunately, guessing and swapping parts is common practice these days since alot of people, even those who work in the industry, have a poor understanding of modern vehicle systems. The P0171 "Fuel system lean bank 1" is a common problem and is fairly easy to pinpoint. It is almost never caused by an O2 sensor. There are several fault codes specific to the 02 sensors. The OBDII system does a good job of testing the O2 sensors. About the only time I see P0171 or P0174" Lean bank 2" in connection with an O2 sensor is when there is also a code for O2 sensor heater circuit fault. When the O2 sensor is too slow heating up on one of the two banks, it can cause that bank to read lean until the sensor finally warms up and starts to read correctly. This can cause a false lean code which is actually caused by a faulty O2 sensor heater. This condition is rare however. The most common causes of P0171 are either unmetered air, like a vacuum leak, or a dirty MAF sensor. To know which it is, you need to connect a scan tool. A generic OBDII scanner will work fine. A graphing scanner is best as it provides a way to see what just happened. Having a helper to read data as you drive will also work. Watch short term and long term fuel trims. They should be close to zero. Less than 10% is acceptable. Fuel trims that are high at idle and normal under load indicate unmetered air leaking into the intake. Normal at idle and lean under load indicates a dirty MAF sensor. Lean at idle and under load is also most likely a dirty MAF sensor. MAF sensor cleaner is cheap and a good place to start before replacing an expensive sensor. Poor fuel supply is also a possible cause of lean AFR under load, but it's less common.