Tech Area

V6 Sensors

Question: Here are the symptoms:
1) car starts poorly (starts & dies, must keep pumping gas pedal)
2) check engine light comes on after the engine warms up some and stays ON
3) car runs like crap, once it does warm up

I checked the error codes, and get ONLY an error 15 which indicates "Coolant Temperature Sensor (CTS) - signal voltage is high"

I have replaced the temp sensor (the one near the distributor) 2 times just in case of a 'bad' one (so we've had the original plus 2 NEW ones in there) with no change. I inspected the wires as far back as I could in the engine compartment and have found nothing wrong (no breaks or shorts). In order to inspect further to the ECM I have to pull the inside of the car apart, so I ordered a new ECM (rebuilt from the Fiero Store) so I don't have to tear it apart again or leave it torn up and risk loosing parts.

I'm working on a 1988 GT - V6, 5 spd ( with stock engine )

Am I missing something ? Is there another sensor that I'm not aware of ?

Any thing else besides the ECM that could be causing the problem ?

Answer: There are 4 temp related sensors/senders on a V6 Fiero engine. The one changed in this email (in the head, sorta under the coil) is for the gauge/temp light and will NOT set a code 15.

2 others stick straight up from the intake manifold between the thermostat housing and the forward valve cover. The single wire sensor closest to the valve cover (squeeze connector to remove) is the radiator fan switch. The other is a 2 wire connection held by a spring wire clip. It is the cold start injector switch. Neither of these will set a code 15.

The last sensor is for the ECM. If faulty, it WILL set a code 15. It is also the hardest to find/see. It is located on the front of the intake manifold just above the timing cover and points straight out toward the pass rear wheel. It is covered by the wiring bundle that comes across the front of the engine under the EGR solenoid.

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