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Discussion Starter · #1 ·
Hi there.

My check engine light went on today - how frustrating this one always is. The car does not run any differently than before. I have tried the gas cap trick and nothing. About 5 months back this light came on and I had the O2 sensors changed. Anyone have any ideas on this one.

Ideally I would love to scan and get the codes myself, but do not have access to a scanner. I am in canada, so the autozone deal doesn't apply here.

Thoughts, recommendations??

Thanks all.
 

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Buy a generic OBDII scanner or VAG-COM cable if you have a laptop. Scanner less than $50 on ebay and cable about $20 to be used with free Ross-tech software. Scanner can be used on other vehicles also while the VAG-COM cable / software use is specific to VAG cars. Otherwise, I (and my guess others) can't help without codes unless others are psychic.
 

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Grinding Gears...gone fishing!
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can you tell us some more about your car???
dont be so vague when asking for help.
year miles motor...

for all that thread says you can be talking about a toyota.
 

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Discussion Starter · #4 ·
Additional details

Here are some more details:

- 2001.5 Passat GLX V6 (2.8L?)
- NOT 4-motion
- 61,000 KMs

Hope that helps.

Thanks.
 

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did you have all four o2 sensors replaced? or just the front or back? if there is an autozone or such close, they'll scan your car for free that would be a good cheap start to solving it
 

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The fact that you have a CEL with no noticeable change in performance suggests that you have a bad sensor. Engine sensors are notorious for failing so slowly that the driver never even notices the engine's performance is dropping until the sensor dies completely and the ECU panics.

Furthermore, the ECU is still quite capable of making the car run without proper sensor readouts, because it has a pre-programmed map of throttle-position vs. engine speed vs. fuel injection rate. The MAF and the O2 sensors are helpful for "stretching" the map to fit real-world conditions as precisely as possible, but if you've ever driven a car with a carburetor, you'll realize that the Air/Fuel ratio can actually be a good ways off from ideal and the car will still run.

- - -

Alternately, your catalytic converter could have emptied itself out all over the road somewhere and your spiffy new O2 sensors are just now realizing it.
 

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Hi there.

My check engine light went on today - how frustrating this one always is. The car does not run any differently than before. I have tried the gas cap trick and nothing. About 5 months back this light came on and I had the O2 sensors changed. Anyone have any ideas on this one.

Ideally I would love to scan and get the codes myself, but do not have access to a scanner. I am in canada, so the autozone deal doesn't apply here.

Thoughts, recommendations??

Thanks all.
usually a vagcom for a DTC willl tell you exactly which o2 sensor it is,when you say the CEL was on and had the o2 sensors changed you only had to do the one or ones needed since there are four(4) of them.you still need to go to a garage that delas with german/import cars and have it scanned again.
 

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Grinding Gears...gone fishing!
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you most likely need to change the temp sensor if you never have.
that is a judgment guess.
 

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Without a scan, guesses are all you will get here. I would check the vacuum lines, you may have broken one. Check both the rubber and the plastic lines.
 

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Discussion Starter · #10 ·
PZ Reply

Without a scan, guesses are all you will get here. I would check the vacuum lines, you may have broken one. Check both the rubber and the plastic lines.

PZ, how do I check the vacuum lines and what am I looking for?

Thanks.
 

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PZ, how do I check the vacuum lines and what am I looking for?

Thanks.
Install a vacuum gauge and look for a hot-idle reading of around 20 inches of mercury. If you're getting substantially less than that, you have an air pressure leak. Plus, the gauge will kinda look like you've turboed your car. :thumbup:

I wish I could remember who it is that makes all different manner of gauges with multiple colored backlights built in. I know someone was asking about inexpensive gauges a while back.
 

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You could also look at the vacuum lines themselves. There are several plastic ones and many small short rubber ones. Take off the engine cover and trace each hose end to end, look for breaks or tears.

The plastic one from the right front valve cover to the fender and the one connecting the 2 combi valves at the back of the engine are common failures.
 
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