Q: My van will only start when the check engine light comes on

I hate to be the stereotypical dealer mechanic, but the issue may be “normal.” According to the GMC bulletin PIC6106, the display screen may reset during high load situations. This is considered normal and will most commonly happen during a...

Hello. The erratic idling could be caused by several things: You could have a bad mass air flow sensor, the throttle position sensor could be bad, or the idle air control valve could be bad. This could also be an...

Hi there. The effect that this object will have on your vehicle depends on its size. If it is not flat and somewhat irregular, then you should be fine if you leave it in there as it should not interfere...

The timing chain keeps the internal engine components moving in the correct time. Valves have to open and close at specific times in order to avoid contacting pistons, prevent misfires, etc. If the chain breaks with the car engine at...

This may be due to a faulty heater blower motor (https://www.yourmechanic.com/services/heater-blower-motor-replacement) or potentially a bad heater core. As you may know, the heater core is a small radiator like unit that circulates the hot coolant from the engine through the...

The black colored surface on the battery terminal is caused when a battery releases hydrogen as it charges and discharges. This creates a lead oxide that will eventually build up enough to create a low current path to ground that...

Hello, thank you for writing in. With intermittent symptoms, diagnosis can take longer but is typically the same as diagnosing any other starting problem. The main issue is that you can only perform the testing needed when the issue is...

Hi - I suspect the [turbocharger oil seals have blown out](https://www.yourmechanic.com/question/turbocharger-leaking-oil, and are leaking oil into the air intake/intercooler piping. This is also reducing turbocharger efficiency, and power generation. I recommend a loss of power inspection (https://www.yourmechanic.com/services/loss-of-power-inspection) performed by a...

Hello, thank you for writing in. With the check engine light on, we need to start by scanning the vehicle for diagnostic codes to find out why that light is on. We can use the codes to help point us...