Check Engine light with EGR Valve Error Code

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So - your "Check Engine" light came on one evening on the way home from work. It was intermittent at first, but over the next few weeks it stayed on more and more. Finally, you checked with your trusty SHOtimes FAQ and found how to run the EEC-IV error codes, and saw a 33 code (89-91) or a 332 code (92-95) - "EGR valve opening not detected". This can show up in both the engine-on and engine-off tests.

You might be tempted to replace the $70 EGR valve - but this is probably not the problem. The most common problem is that the EGR valve feeds into a tube machined into the intake manifold, and, where this tube lets out inside the intake, it is necked down to a cross-section of a few mm's. Often referred to as nostrils. This gets coked up, blocking off the EGR flow.

To see if this your problem, remove the small plastic tube from the EGR valve, and attach another length of tube to the valve. Start the engine and suck on the tube. If the engine revs go down, the nostrils are clear. If they stay the same, the nostrils are blocked. The coke must be removed.

To do this, remove the throttle body from the manifold (because the throttle butterfly will prevent you from reaching effectively into the intake).

If you now look into the intake, you will see four nostrils. The lower two are the ones that will be obstructed by coke deposits.

Now, using something like a 2mm allen wrench or baling wire, some carb cleaner and an air line, clean the nostrils in the manifold.

Two other possible mechanical problems on MTX cars:

- The small sampling tube going from the EGR tube to the PFE Sensor is blocked. Remove the PFE Sensor from the tube, and attach a small tube to it and blow (don't suck as you might inhale soot). If it's blocked, it will need rodding out. A tough job as the tube is so small and goes through a 120 degree angle. I have had success using a length of bendable speedo cable in a drill.

- The bellows in the EGR Tube below the valve is split, or the small sampling tube going from the tube to the PFE Sensor is blocked. You would hear and feel exhaust gases escaping.

Probably, the Check Engine light will now be behaving itself.