'04 FocusSVT Flashing check engine light

Last night the car started running like shit while leaving a parking lot. I pulled into a spot to look things over and found a vacuum line broken. I got a piece of rubber hose and to patch it together but it still ran like shit.

While driving it home the check engine light started flashing and it was acting like it was at least one cylinder down. The cat was glowing red too. I'm going to check the plugs to see if the loss of vacuum put it in a rich condition and check cylinder pressure.

Has anyone seen this before?

Thanks for any info.

Plugged cat? Happened on my last truck.

flashing typically indicates a misfire or severe detonation. Check the plugs and coils. If the cat was glowing red, that means a lot of unburned fuel was getting to the catalytic converter.

If you don't have a code reader, head to Autozone or whichever is closer and they'll scan the codes for free.

Also drive it as little as possible. Could cause engine damage.

08mojo said:

flashing typically indicates a misfire or severe detonation. Check the plugs and coils. If the cat was glowing red, that means a lot of unburned fuel was getting to the catalytic converter.

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This if it’s flashing.


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Forgot to add the picture of which vacuum line it was. Not sure if it matters.

if that's the vacuum reference to the fuel pressure rail, no doubt it was dumping a lot of fuel into the engine and it wasn't happy. That should have cleared up though when you repaired the vacuum line.

08mojo said:

if that's the vacuum reference to the fuel pressure rail, no doubt it was dumping a lot of fuel into the engine and it wasn't happy. That should have cleared up though when you repaired the vacuum line.

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It got a little better, but was still bad.

I'll recheck the line with other than cell phone light this weekend.

Stanley said:

It got a little better, but was still bad.

I'll recheck the line with other than cell phone light this weekend.

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I’d check the dip stick and if your oil reeks of gas I’d change it.


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BlksvtCobra01 said:

I’d check the dip stick and if your oil reeks of gas I’d change it.


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Good idea, didn't think of that.

Stanley said:

Last night the car started running like shit while leaving a parking lot. I pulled into a spot to look things over and found a vacuum line broken. I got a piece of rubber hose and to patch it together but it still ran like shit.

While driving it home the check engine light started flashing and it was acting like it was at least one cylinder down. The cat was glowing red too. I'm going to check the plugs to see if the loss of vacuum put it in a rich condition and check cylinder pressure.

Has anyone seen this before?

Thanks for any info.

Click to expand...

Flashing cel is a misfire, cat is glowing due to heat

If it dumped enough fuel the cat could be clogged up. Enough fuel will ignite in the honeycomb material and melt causing blockage.

Check to make sure the plugs weren't fouled out either. Change the plugs and check for backpressure in the exhaust stream through an o2 sensor port. Napa or Autozone has the gauge for rent.

Once you reset everything. Disonnect battery overnight. Should reset the ecu. Best of luck man.

Most likely cause is a failed ignition coil pack. Usually upon removal you will find a crack in the resin potting, but not always. You can test the coil with either a spark tester (a grounded plug) or by carefully removing each lead from the coil and listening/watching for the arc. Start at the coil and work your way down the secondary system with the spark tester to isolate the coil from the wires as the failed part.

Also remove the wires and inspect for oil in plug wells. If any oil is found replace the valve cover gasket and spark plugs.

As stated earlier the glowing cat is a result, and not a cause. A lean/rich condition from a failed vacuum line will NOT cause a glowing cat. It is glowing due to heat from the excess fuel from the misfire, not any type of lean condition.

Finally, if you have a quality scanner capable of Mode 6 data you can monitor the catalytic converter's efficiency in real time. This would be good to know as a glowing cat will result in catalyst efficiency failure or restriction.