1993 Ford Explorer how to clear codes 411 and 412

MEANDTHREE

MEMBER
1993 FORD EXPLORER
6 CYL
4WD
AUTOMATIC
150,000 MILES

We were given this 1993 Ford Explorer and do not know much about it but it ran fine until a few months ago. We have replaced the TPS (throttle position sensor), the IAC (idle air control) valve, both oxygen sensors, fuel filter, plug wires, and plugs. It now gets worse gas mileage (we were getting 16-18 mpg and now we are get 10-12mpg) than before and the engine light comes on and off. We hooked it up to a code reader and therer we no code with the KOEO but with the KOER we get code 411 and 412. The codes that are in memory are 157, 172, 173, 176, 177, 179, 188. How do we get rid of codes 411 and 412 and what could be causing our bad gas mileage?

3 Replies

2CARPRO JACK

MECHANIC
11,533 POSTS

Need to know ifit is a 3.0L or a 4.0L so I can look up the codes. On OBD-1 vehicles you can usually unhook the battery for a few minutes and it will clear the codes, if they come right back they are "hard" codes and need to be repaired. Get back to me with engine size so I can look them up to see wha tis going on

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Wednesday, February 10th, 2010 AT 7:55 AM

MEANDTHREE

MEMBER
1 POST

It is a 4.0 L engine. We have checked the spark plug gaps, and tested the spark plug wires and both seem to be fine. (They were changed not long ago). My husband also changed the serpentine belt, could the timing chain be off a tooth? Would that cause bad gas mileage? Thanks for any help.

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Monday, February 22nd, 2010 AT 12:22 PM

2CARPRO JACK

MECHANIC
11,533 POSTS

411-Cannot control RPM during KOER low RPM check

412-Cannot control RPM during KOER high RPM check

Both of these codes are related to the IAC (Idle Ar Control) circuit. Possible causes are the IAC valve is bad, the throttle stop has been adjusted out of range, a bad ecm or wiring. If the throttle (idle) has been adjusted it needs to be put back where it was and the IAC valve repalced. Anytime the light is on the mileage/performance will be hurt a little

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Tuesday, February 23rd, 2010 AT 7:49 AM