Check Engine Light - Ford 460

[elgarc]

The check engine light comes on only after reaching cruising speed. Thought it might go away, but has been doing it for a month now. Since it's on a 37' motorhome, it's way inconvenient to get into a shop for analysis. Most dealers I've come across don't even work on MHs. I'm thinking might be oxygen sensor? Happened coincidentally with replacing the water pump (which required taking a buncha stuff off). Have checked for loose wires, or wires I mightn't have reconnected but everything looks good. ??

Thanx,
elgarc

[bejay]

you should have it diagnossed by a shop or atleast have codes read you may be able to do this yourself on a 95 or older model using a analog voltmeter or a simple code reader, without doing the above you would just be guessing at what might be setting off the engine light as there is many sensors that could set it off.

[jon_k]

You can grab the diagnostic codes easily from your car. Whenever your car shows "check engine light" then your computer detected an error (a value from an oxygen sensor above or below expected values etc) and will record it in the diagnostic memory.

That is where OBD systems come in, a way to grab these codes from the computer.
There are two types of OBD systems. OBD I and OBD II.

If your car is mid 1980's - 1995 then it has OBD I.
If your car is 1995/96 - current then it is OBD II.

OBD II
Grabbing OBD II codes require the use of a OBD reader which can be aquired at any auto shop (autozone, advanced auto, pepboys.) It's a worthy investment and shouldn't cost more than $95 dollars max. It plugs right in to the diagnostic port (under dash around the parking brake.) and will tell you the codes/error stored in the memory.


OBD I
[edit] Ahh, the information I had here was likley only accurate for Chevy trucks, however if you buy a Haynes Manual for your truck and look up OBD it will tell you how to grab the codes from your truck.

[bejay]

obd 1 diagnostic connectors varied greatly between ford, gm and chryslers along with how you retrieve codes while that info is fine for your chevy it is not going to work for ford vehicles.
obd2 connectors are all the same in appearance but can use different keys in your scantool connector to make them all compatible.