code 23 and 43
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Junior Member
Joined: Dec 2004
Posts: 2
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From: So Cal
Car: 91 Bmw/ 89 RS
Engine: Stock 305
code 23 and 43
Whats up guys new to the forum.
i pulled these codes and then just recently started dying after driving for a mile and coming to a complete stop. well any distance over a mile i have noticed this problem. it will die and then not want to restart. Code 43 is misfire right?? or am i looking at a deeper problem like this guy
heres the link to the problem
what do you think?
i pulled these codes and then just recently started dying after driving for a mile and coming to a complete stop. well any distance over a mile i have noticed this problem. it will die and then not want to restart. Code 43 is misfire right?? or am i looking at a deeper problem like this guy
heres the link to the problem
what do you think?
Supreme Member
Joined: Feb 2004
Posts: 1,231
Likes: 1
From: Greenville, SC
Car: 1991 Chevy Camaro
Engine: 305 TBI
Transmission: 700R4
Axle/Gears: 3.42
Code 25-MAT Sensor- Temp high, poor electrical connection, open or short in circuit; defective MAT sensor; defective ECM
Well, the MAT (Manifold Air Temperature), more commonly known as the IAT (Intake Air Temperature) sensor, is located towards the rear of the air filter housing. It's round and has a 2-wire connector going into it. Check the wiring to it for burns, cracks, cuts, or chaffing. With the KOEO (key on, engine off), disconnect the 2-wire connector and check for 5-volt reference through one of the wires and ground through the other wire, just to make sure the wiring is not at fault. Check the resistance of the MAT, or IAT sensor. If it's out of spec, than it's time to replace it. Here's a chart to compare:

Code 43-Electronic Spark Control- Poor electrical connection, open or short in circuit; defective ESC module; defective knock sensor; defective ECM
This code generally comes up if the engine timing is off, if the engine is detecting a lot of knock, or if the car is overheating. Have you checked or changed the timing recently? Is the EST-bypass wire disconnected (tan and black wire near the passenger side strut tower with a black connector on it. I'd check all of the wiring to and from the ESC module and knock sensor for burns, tears, cracks, etc.
Don't forget that the computer will store codes in it's memory for a while, so it may be a good idea (if you can) to disconnect the negative battery cable for a minute, reconnect it, and test drive the vehicle again, to make sure that both of these codes are current.
Well, the MAT (Manifold Air Temperature), more commonly known as the IAT (Intake Air Temperature) sensor, is located towards the rear of the air filter housing. It's round and has a 2-wire connector going into it. Check the wiring to it for burns, cracks, cuts, or chaffing. With the KOEO (key on, engine off), disconnect the 2-wire connector and check for 5-volt reference through one of the wires and ground through the other wire, just to make sure the wiring is not at fault. Check the resistance of the MAT, or IAT sensor. If it's out of spec, than it's time to replace it. Here's a chart to compare:

Code 43-Electronic Spark Control- Poor electrical connection, open or short in circuit; defective ESC module; defective knock sensor; defective ECM
This code generally comes up if the engine timing is off, if the engine is detecting a lot of knock, or if the car is overheating. Have you checked or changed the timing recently? Is the EST-bypass wire disconnected (tan and black wire near the passenger side strut tower with a black connector on it. I'd check all of the wiring to and from the ESC module and knock sensor for burns, tears, cracks, etc.
Don't forget that the computer will store codes in it's memory for a while, so it may be a good idea (if you can) to disconnect the negative battery cable for a minute, reconnect it, and test drive the vehicle again, to make sure that both of these codes are current.
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