2g Throwing some CEL codes

[grans0o]

My friend just bought a 96 TSi Fwd. The Check engine light has been one since he bought it, got it checked out and these are the codes that it threw.
P0170- Fuel Trim Malfunction (Bank 1)
P0443- Evaporative Emission Control System Purge Control Valve Circuit Malfunction
P0125- Insufficient Coolant Temperature for Closed Loop Fuel Control

I'm not exactly sure what these mean or what could be causing them. If you could help me out I'd appreciate it.

Thanks,
Paul

 

[CyberEye]

My friend just bought a 96 TSi Fwd. The Check engine light has been one since he bought it, got it checked out and these are the codes that it threw.
P0170- Fuel Trim Malfunction (Bank 1)
P0443- Evaporative Emission Control System Purge Control Valve Circuit Malfunction
P0125- Insufficient Coolant Temperature for Closed Loop Fuel Control

I'm not exactly sure what these mean or what could be causing them. If you could help me out I'd appreciate it.

Thanks,
Paul

check to make sure the EGR and Charcoal Canister hasn't been messed with/all vac lines are hooked up, replace the thermostat and check the coolant temp sensor. As for the P0170, people get that for all kinds of reasons. I'd check the O2 sensor first for that.

 

[blcknspo0ln]

replace your thermostat for the last code..

 

[blackGSX2g]

P0170- Fuel Trim Malfunction (Bank 1)

Check operation of your front o2 sensor. Voltage should cycle between 0.00v and 1.00v. If it doesn't move, or moves very slowly, you need a new front o2 sensor. If you've got a logger, try looking at your bank 1 fuel trims. If your o2 sensor is dead or dying, your trims will probably be a number around 17 and won't move much.

P0443- Evaporative Emission Control System Purge Control Valve Circuit Malfunction

Check to make sure all of your solenoids on your firewall are plugged in, then verify that all the hoses are hooked up to their respective source.

P0125- Insufficient Coolant Temperature for Closed Loop Fuel Control

Check the coolant temperature sensors. If the sensor dies, it won't give the ECU the necessary signal to go into closed loop mode when the motor is completely warmed up. If the sensors check out, then check the thermostat. What is your stock coolant gauge reading at when its warmed up?

 

[grans0o]

Check the coolant temperature sensors. If the sensor dies, it won't give the ECU the necessary signal to go into closed loop mode when the motor is completely warmed up. If the sensors check out, then check the thermostat. What is your stock coolant gauge reading at when its warmed up?

The stock coolant gauge is reading at barely below the very center of the gauge when fully warmed up. Does gas mileage suffer when the ECU isn't allowed to go into closed loop mode? Thank you for everyone's help!

 

[blackGSX2g]

The stock coolant gauge is reading at barely below the very center of the gauge when fully warmed up. Does gas mileage suffer when the ECU isn't allowed to go into closed loop mode? Thank you for everyone's help!

When you are in closed loop operation, your ECU takes input from the o2 sensor to control the fuel trims. When you aren't in closed loop, the ECU basically ignores the o2 sensor's output. Your gas mileage will plummit without a working o2 sensor. I went from around 14mpg to 24mpg (city) by getting a new o2 sensor and laying down a decent tune.

In your case, I would check the coolant temp sensor or a thermostat. Your car is in open loop mode until the car reaches operating temperature. This is so your car warms up faster. If the ECU never sees full operating temperature, it will still consider the car in 'warm-up' mode and ignore the o2 sensor.