Contour Enthusiasts Group Archives Forums General Troubleshooting Coincidence between Coolant Flush & ECT sensor DTC

I already combed through "search" to find any insight to an intemittent CEL on my '95 Mystique 2.5l V-6 with OBDI system. Not much luck. First, a brief intro to what led into its ugly head. I drained & backflushed the relativly clean coolant very throughly. I refilled system and ran to operating temp. Did test drive after t-stat opened & guage reading between O & R and CEL came on for a few seconds. Now ever since the CEL will come on briefly and go out. Always when in closed loop and usually when decellerating or after getting off hwy driving 20-30 mph. I have no drivability problems, great heat, and normal temp guage readings. I checked coolant level, connections, vacuum lines and any other obvious points.

I pulled out my scanner and here are my results:

KOEO- DTC 116- ECT Sensor out of Range

KOER- DTC 332- EGR did not open or respond during test

Memory- DTC 332- EGR did not open intermittantly.

Has anyone have any logical explanations to this coincidence? Did the ECT sensor get disturbed? The voltage readings fully warm @ idle was .68 @ 184 deg F. The normal reading should be between .70 to .40 volts. Does anyone know the point where the CEL will be set? As for the EGR code, would there be any relationship between the two or it is possibly the EGR passages are restricted? Could the DTC 116 cause a DTC 332? Could the ECM be tricked into not regulating EGR operation when the ECT is out of range? The proper repair order is to fix all KOEO codes first and then go after any KOER and Memory codes.

How common is this sensor going out of range? Others having this code, did replacing the sensor solve the issue? I know where its located but I would like to be sure before I start freezing my fingers digging out this sensor! Cleaning out the EGR passages is a little more accessible (Is throttle plate gskt reusable?). Any educated information would be appreciated. Please no foolish guessing. I am sure there is a local expert out there who could steer me in the right direction. Thanks

How cold was the car when you did the koeo test? if it was below operating temperature, it'll set this code - it means nothing by itself. The egr codes are probably caused by the dpfe, but there are egr passages in there that can be clogged too. If your scanner has the capability, pull up the ect pid - should be oeprating temp when it is warmed up. Check the pfe pid and then use active commands to open the egr valve - the pfe voltage should rise and the engine should run rough. If the voltage doesn't rise, and the engine runs rough, then the sensor is bad. If the voltage doesn't rise and the engine still runs smooth, check the vacuum supply to the egr valve. If the vacuum is ok, pull the throttle body off and clean the egr passages.

I wanted to post back and let fellow CEG'ers what I did to correct my DTC 116 and DTC 332 following some PM service. I cleared these codes and ran to operating temperture to perform add'l tests. I only got DTC 332 relating to the EGR system. I did a through search and read up on the DPFE, EVR, and EGR system. Being a closed looped feed back system and the EGR passages never being inspected or cleaned out, I decided to tear down the throttle plate and see into the darkness of hell. The 3 notches on the intake manifold were almost completly plugged up with hardened carbon deposits. Long story short, I cleaned the passages and throttle plate as clean as a whistle and buttoned everything back up and crossed my fingers. So far so good-No CEL's. By the way, I got a new TB gasket in a Felpro # for a $1.98.

So I have come to the conclusion with the V-6 motor. Perform a EGR passage service every 30,000 to 40,000 miles and one will prevent many emission problems. I still think it was a strange coincidence I got the CEL after doing some straight forward service work. I guess I must of disturbed the "electrical Gods" living inside the PCM.