Help! Thermostat replaced, engine light still on, drive cycles?

LIZ1111

MEMBER
2002 VOLKSWAGEN JETTA
113,000 MILES

I need to get the vehicle certified for registration and it failed the smog emissions test.

So, my mechanic just replaced the thermostat and now I have a gauge that works, (also my heater works again!)

However, the engine light is still on. Will this go off by itself? How many drive cycles will it take to get eveything ready for the emissions test?

Thanks in advance. Farvehgnugen!

4 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

The thermostat will not turn the engine light on unless it overheats. Have the computer scanned to identify trouble codes.
Most parts stores will scan it for free.

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Friday, February 10th, 2012 AT 7:12 PM

LIZ1111

MEMBER
2 POSTS

Thanks. Do you know anything about the engine cycles to reset the other things that need to be reset in order to pass the smog emissions? There are 4 that need to be 'ready' and after the mechanic visit, I only had 1 'ready'.

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Friday, February 10th, 2012 AT 7:15 PM

F4I_GUY

MECHANIC
3,302 POSTS

Replace the ECT if the sensor body is all black. That is why your engine light is on and is not turning off. There is an updated green sensor.

After replacing it, clear the fault. I don't know why you're waiting for it to shut off? Go to auto zone, they'll clear it for free.

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Tuesday, February 14th, 2012 AT 4:02 PM

EXOVCDS

MECHANIC
1,883 POSTS

Clearing alone will not get him passed smog. Like he said, the 4 readiness monitors that are "checked" need to pass readiness by the ECM first. Readiness setting can be performed by following a procedure. What engine size?

@ Jacobandnickolas, a faulty thermostat WILL set a "Cooling System Performance Malfunction Code".

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Saturday, February 18th, 2012 AT 9:57 PM