1996 Explorer - P0153

My Explorer with a 4.0L engine has a solid check engine light. The code is P0153 which says bank 2 sensor 1. Can anyone tell me what this means? I think it is an O2 sensor. Whch side of the engine is bank 2? Also I noticed that at around 70 MPH on an incline the engine seems to misfire but I do not see a change at the tachometer. Could the O2 sensor cause this? Thanks.

The code actually says the O2 sensor is slow to respond. This could be due to a worn O2 sensor, but it could also be due to a vacuum leak, dirty MAF sensor, fuel pressure issue, etc.

If you decide to start with the O2 sensor and see if that helps, bank 1 is the bank of cylinders on the passenger side of your truck (assuming you're in the U.S.). Bank 2 will be the bank on the driver's side (same assumption). Sensor 1 will be the sensor before the catalytic converter.

The misfire underload is probably the cause of the P0153, and that misfire is not likely due to the O2 sensor. I'd suggest you verify no vacuum leaks exist and go through the normal tune up items. When was the last time a tune up was performed on the Explorer? If you are using one of the oiled, reuseable air filters, you may be able to fix the code and the misfire simply by cleaning the MAF sensor elements.

-Rod

Rod, Thanks for the response. I have since learned that there are 2 codes. P0401 is the first and P0153 is the second. I did puul the plugs and found them to be shot. I replaced the plugs, checked for vacuum leaks and reset the codes. They returned after about 10 miles of driving. I also blew out the air filter. Any other advice? Also, is the MAF sensor in the air filter duct? What would I clean it with? The car was purchased a few months ago and it has 116,000 miles. It was dealer maintained but I guess it was due for a tune up. Thanks again. Bob

You should consider completing the rest of the tune up - spark plug wires, fuel filter, fuel injector cleaner in the fuel tank.

CRC makes a spray cleaner specifically for the MAF sensor. It's around $7 a can, but much less expensive than a new MAF. You may also need a set with a T15 (I think) Torx security bit to get the MAF out. The MAF will be in the intake air tubing between the air filter housing and the throttle body. There are probably 5 wires going to it (3 wires for the MAF and 2 for the integrated Intake Air Temp sensor).

-Rod

According to the factory service manual, the P0401 indicates there is insufficient EGR flow. You should consider inspecting the EGR passages and throttle body as well as the EGR valve for carbon build-up. If you don't find any significant build up in those locations, you could have a faulty DPFE/EGR pressure sensor. This is a pretty common part to fail on many Ford products.

-Rod

Rod, I changed the ignition wires, plugs, and fuel filter and cleaned the MAF sensor and butterfly valve. The car seems to be running better and the P0153 code has not come back but I still have the P0401. I will pull the EGR valve and check for buildup. Thanks again. Bob

Anyone who is interested,

The P0401 returned about 2 weeks after I did the tune up. I replaced the DPFE sensor and the code has not returned. It was pretty simple to change.

Thanks for posting a follow-up!

-Rod