The engine light comes on my car every couple of weeks. The engine is running fine though.

P0 687
ECM / PCM
Control Circuit High

What do these codes mean? I am suppposed to take the car on a road trip next weekend and am litttle concerned with light on. Is it safe to drive? Mechanic can't work on the car this week; a Mark II and E type need to go out the door, so the short week is dedicated to them.

 

I checked error code PO687 on this site with no response: Jaguar P0301 OBD/DLC Error Code - Cylinder 1 Misfire Detected. They say it does not exist, but of course it does. Suggest you Google search. In the meantime, you can usually "clear" the code by rebooting your ECU - very simple to do. Just detach battery cables at the battery; and then hold the cables together for about a minute.

 

Here are details on the error code:

Generic OBD Error Code Details for P0687
ECM/PCM Power Relay Control Circuit High

What does this mean?
OBD Code P0687refers to The Engine Control Module (ECM) has detected a high voltage condition to the ECM.

Symptoms
Possible sumptoms of OBD code P0687
- Engine Light ON (or Service Engine Soon Warning Light)

Causes
Possible causes of OBD code P0687
- Weak battery- Low voltage while cranking
- Poor engine control module electrical connection
- Open or short engine control module circuit

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This morning the engine light is off. I just hope there is not a repeat of: https://www.jaguarforums.com/forum/x...-barfed-84569/

 

The fact the engine light is off again suggests a transient fault rather than a component failure.

A bad connection, short or open circuit in the Control Module circuit wouldn't go away by itself.

An out-of-range signal from the Control Module to the ECM or a low battery would trigger the light and then disappear as the signal came back within range or the battery charged.

Graham