1994 XJ Code 17

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Dec 22, 2013 | 07:48 PM

Programbo

Thread Starter

CF Veteran

Joined: Jan 2009

Posts: 1,964

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From: Baltimore, Maryland

Year: 1994 1993

Model: Cherokee

Engine: 4.0

1994 XJ Code 17

My '94 XJ has been idling lower than normal and my MPG seems a bit down. Today I decided to check my codes since the check engine light was coming on more than normal. (It's been on regularly for a O2 sensor code) Today there was a new code. 17. Which my manual says is "Engine running too cool" So my plan is to swap out the coolant sensor and thermostat. Is there anything else to check? Is there anyway a "running to cool" could affect MPG? I realize the O2 sensor will affect that but I've been getting the O2 sensor code for awhile now and this newest MPG loss seems related to something new. Thanks

Dec 22, 2013 | 09:09 PM

fatbill

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Joined: Jul 2011

Posts: 73

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From: nova

Year: 1996

Model: Cherokee

Engine: 4.0

is the temp low on the gauge? like 150 or so?
your thermo probably failed open and the pcm is trying to warm it up by making the mixture fat.
get a good thermostat and install it.

Dec 22, 2013 | 09:34 PM

Programbo

Thread Starter

CF Veteran

Joined: Jan 2009

Posts: 1,964

Likes: 6

From: Baltimore, Maryland

Year: 1994 1993

Model: Cherokee

Engine: 4.0

Quote:

Originally Posted by fatbill

is the temp low on the gauge? like 150 or so?
your thermo probably failed open and the pcm is trying to warm it up by making the mixture fat.
get a good thermostat and install it.

Yes the gauge has been a bit low lately but I was thinking my coolant temp sending unit was failing since it's only Crazy Glued together