I'm throwing a code. Anybody know what code 41 is on a '92 F150, 5.0, manual tranny? I can't find my Haynes manual.

 

HEGO Fault Code Sensor Definition
41 right or rear system indicates lean.

Possible Causes:

Fuel injectors
HEGO sensor
Thermactor
PCV
Vacuum
CANP
MAP sensor

 

what's an HEGO sensor? Is that the same as the O2 sensor?

 

Yes it is.
Heated Exhaust Gas Oxygen sensor.

 

Before I start troubleshooting this code, I was wondering if anyone had any suggestions as there are other symptoms/noises that started the same time at the same time the CEL came on. When the CEL came on I started hearing a rattling/humming noise coming from the front of the cab on the passenger side. It sounds like the clutch throw out/release bearing going, so I assumed that's what it was, but now I'm wondering if it's something else related to the CEL code 41. I also started smelling anti-freeze at the same time, but I'm pretty sure that's a heater core and an entirely separate issue. Any suggestions would be appreciated. Thanks.

 

The rattling could have been pinging from a lean mixture (injectors above) and a lean mixture could have caused the 41.
A lean mixture may have been caused by the fuel pressure being low and the low fuel pressure could have come from a fuel pump going bad (humming). The humming sound could have also come from a sticking fuel pressure regulator and it would have also caused the pinging and the 41.

 

Thanks, I'll start looking there and I'll test the MAP and O2 sensor with a voltmeter.