HELP Code P0155

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Mar 6, 2018 | 01:23 PM

Ashley Marie Hicks

Thread Starter

Newbie

Joined: Mar 2018

Posts: 1

Likes: 0

Model: Cherokee(SJ)

HELP Code P0155

CODES?

P0155
HEAT MAL
BANK 2 DOWN SYSTEM

my engine light came on this morning this is what they read to me a the auto store.... help me understand....

Mar 7, 2018 | 07:29 PM

89Laredo

CF Veteran

Joined: May 2009

Posts: 10,423

Likes: 61

Year: 2000

Model: Cherokee (XJ)

Engine: 4.0

A/F SENSOR B2 S1 HEATER CIRCUIT MALFUNCTION

Sounds like your rear oxygen sensor heater is bad. Possibly just the sensor, maybe a relay or fuse. Hopefully someone with more obd2 knowledge will show up.

Mar 7, 2018 | 09:50 PM

GreaseMonkey17

Senior Member

Joined: May 2017

Posts: 645

Likes: 34

Model: Cherokee

You need to have the downstream oxygen sensor replaced. Your oxygen sensors monitor the air/fuel ratio your engine is burning and adjusts various components of the engine according to that reading to make it run as smoothly as possible . A lot of times you will get a code and not notice a difference but sometimes they’ll cause rough idle , stalling , poor performance , bad gas mileage etc . It is threaded into your exhaust after the catalytic converter . What year Jeep and what engine do you have ?

Mar 8, 2018 | 07:12 AM

tjwalker

CF Veteran

Joined: Nov 2010

Posts: 5,840

Likes: 117

From: In the middle of Minnesota!

Year: 1999

Model: Cherokee

Engine: 4.0

Link to information on P0155. Be sure to check the mini fuse in the power distribution center (black box under the hood) as the heater circuit for the oxygen sensors IS fused.

https://www.yourmechanic.com/article...-jamahl-walker

Mar 8, 2018 | 11:24 AM

89Laredo

CF Veteran

Joined: May 2009

Posts: 10,423

Likes: 61

Year: 2000

Model: Cherokee (XJ)

Engine: 4.0

Apparently my brain wasn't working yesterday. Crawl under and make sure the rear oxygen sensor harness isn't damaged or rubbing on the driveshaft or exhaust. If it is, repair the harness and check the fuse/relay for the rear oxygen sensor heater. This is actually a common problem and can cause lots of issues.