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24/06/2021 10:25 pm
Topic starter
1999 Saturn Sc1
Code P0404 P0300 also CTS shows 1/4 up on gauge before even starting. Struggling to start but always does and drives fine when I get going. Your in put as what to do first. I want to myself if possible. Not a lot of funds to take in.
Thanks Susan
1 Answer
3
25/06/2021 10:35 am
The PCM determines the EGR's pintle position using inputs from the Throttle Position Sensor (TPS), the Manifold Absolute Pressure Sensor (MAP) and, the Engine Coolant Temperature Sensor (ECT).
On cold start the EGR valve should be closed.
Since your ECT gauge is 1/4 up on cold start it's likely the computer is opening the EGR valve a little thinking that the engine is warmer than it is.
A good place to start may be to replace the ECT sensor
