rkbessey

Recently my Check Engine Light came on and the dealer told me I needed a new A/F Sensor - cost $600. I ran over to AutoZone and hooked up the code reader and got P1155 Air/Fuel Ratio Sensor Heater Circuit Malfunction (Bank 2 Sensor 1). The guy at AutoZone seemed knowledgable and pointed out that it would be the sensor up in the front that is quite easy to access. He all recommended I clean off the Mass Air Flow Sensor first (which i did). Reset the codes and the CEL came right back on with same P1155 Code. While looking online, I noticed a few sights claim P1155 is Bank 1, not Bank 2 which would be much more difficult to get to.

My Question then is this - can I be sure P1155 is related to Bank 2 Sensor 1? and if so, is replacing the Air Fuel Sensor likely going to resolve the issue of the CEL? From reading online it sounds like these sensors get replaced somewhat frequently, but they aren't always bad... is there something else less expensive I should try first?

GEORGE_JET

O2sensor.pdf

My manual indicates that the code is for bank 2, the easy one to get to. I have attached at pdf that shows how to check the sensors heater resistance. You should also check the fuse.

JSM1284

P1155


DTC P1155 A/F SENSOR HEATER CIRCUIT MALFUNCTION (BANK 2 SENSOR 1)

CIRCUIT DESCRIPTION






To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three-way catalytic converter is used, but for the most efficient use of the three-way catalytic converter, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel ratio.

The oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity of the stoichiometric air-fuel ratio. This is used to detect the oxygen concentration in the exhaust gas and provide feedback to the computer for control of the air-fuel ratio.

When the air-fuel ratio becomes LEAN, the oxygen concentration in the exhaust increases and the oxygen sensor informs the ECM of the LEAN condition (small electromotive force: < 0.45 V ).

When the air-fuel ratio is RICHER than the stoichiometric air-fuel ratio the oxygen concentration in the exhaust gas is reduced and the oxygen sensor informs the ECM of the RICH condition (large electromotive force: > 0.45 V ). The ECM judges by the electromotive force from the oxygen sensor whether the air-fuel ratio is RICH or LEAN and controls the injection time accordingly. However, if malfunction of the oxygen sensor causes output of abnormal electromotive force, the ECM is unable to perform accurate air-fuel ratio control.

The main heated oxygen sensors include a heater which heats the zirconia element. The heater is controlled by the ECM. When the intake air volume is low (the temperature of the exhaust gas is low) current flows to the heater to heat the sensor for accurate oxygen concentration detection.

rkbessey

So assuming the ohmmeter measures resistance other then what is specified in the PDF, the next step would be to just replace the Sensor? Is there any advantage to paying a shop to do the work rather then just unscrewing/pluging the old one and connecting the new one?

rkbessey

Also is there anyway to verify I have the correct part number for the new A/F Sensor.

I have part number 89467-33050 as the one that I will need, however, I have made a few phonecalls and saw a different site that had a few different possible part numbers including 89467-48011, 89467-33060, and 89465-48011... I called my nearby dealership and they acted like they weren't sure which part number related to which sensor. Any idea which one is actually the correct part number for Bank 2 Sensor 1?

GEORGE_JET

Since it is the front sensor, it is very easy to measure the resistance without having to remove the sensor. With this code, it is very possible that the sensor is open (ie very high resistance). If that is the case you could easily replace the sensor yourself and save considerable amount of money.
If the resistance is in spec, you would then want to check the fuse, again easy to do.
If you still have not found the problem, you could use the info that JSM1284 uploaded, to check the wiring (if you feel comfortable with that sort of thing).

As far as part numbers, you are bound to find a few different ones. I prefer to purchase universal sensors (I personally prefer bosch), Denso is another popular brand. Universal sensors require you to re-use the original connector. They include crimp connectors with the sensor. I personally prefer to solder the wires, and use heatshrink tubing. Soldering gives you a much more reliable connection.

Bottom line, using universal sensor, and doing all your own work, you would end up spending less than $60.

rkbessey

That all makes sense... Thanks a bunch for your help. I'll post if I run into anymore snags.

JSM1284

89467-33050 $206.66 from dealer

EScrow

$128 shipped. Ebay.

GS4_Fiend

iTrader: (22)

google denso a/f sensor to get cheaper for OEM.