code read - 99 cherokee 4.0

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Apr 28, 2012 | 09:42 AM

99jpclassicxj

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Joined: Aug 2011

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Model: Cherokee

code read - 99 cherokee 4.0

Got a code read yesterday. Guy said it read "left bank lean" which he said could mean a lot of things. Wan'ts me to bring it in for full diagnostic check. The place seemed a little shaky. Is this reading legit?

Apr 28, 2012 | 10:51 AM

Bustedback

CF Veteran

Joined: Feb 2010

Posts: 12,367

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From: Oroville, CA

Year: 1995

Model: Grand Cherokee

Engine: 4.0 with all of the noise and clatter

It's a valid code that could be caused by a vacuum leak (too much air) or low fuel pressure or volume (not enough fuel). If you have a bad feeling about the shop you should get a second opinion, go with your gut.

Apr 28, 2012 | 01:46 PM

tjwalker

CF Veteran

Joined: Nov 2010

Posts: 5,841

Likes: 117

From: In the middle of Minnesota!

Year: 1999

Model: Cherokee

Engine: 4.0

Always best to post the exact code here, so there is no confusion.

I agree with BustedBack. A lean code can be caused by something as simple as a cracked exhaust manifold (common) or a vacuum leak or a fuel delivery issue.

I'd be checking for those things.

And if you take it to the shop, authorize them to do the diagnostic and call you with the results and an estimate on how much to repair.

Apr 28, 2012 | 03:25 PM

CCKen

CF Veteran

Joined: Aug 2010

Posts: 8,357

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From: Canton, MI

Year: 1999

Model: Cherokee

Engine: 4.0

Some code readers have strange diagnostic descriptions that are near worthless. The '99 OBD II uses the following language associated with a rich/lean O2S DTC code. Note the rich/lean correction factors.

1/1 is the upstream (Before CAT) O2S and 2/1 is the downstream (after CAT) O2S. Where's the "Left Bank"?

P0171 (M) 1/1 Fuel System Lean - A lean air/fuel mixture has been indicated by an
abnormally rich correction factor.

P0172 (M) 1/1 Fuel System Rich - A rich air/fuel mixture has been indicated by an
abnormally lean correction factor.

P0174 (M) 2/1 Fuel System Lean - A lean air/fuel mixture has been indicated by an
abnormally rich correction factor.

P0175 (M) 2/1 Fuel System Rich - A rich air/fuel mixture has been indicated by an
abnormally lean correction factor.

Like tjwalker said, you need top post the actual code(s).