Plz help i have a 98 mercury villager i get a code p0135 i changed the front o2 sensor and the back but the thing is it gives me a p0135 02 heather circut the quetion is what could it be (a) pcm or somthing else help plz

replace it


P0135 OBD II Trouble Code O2 Sensor Heater Circuit Malfunction Bank 1...

Check the electrical connectors which connect to the O2 sensors for corrosion and improperly high resistance.

Fords are bad about vacum leaks, check all vacum hoses repair as needed.Vacum leak will give an o2 sensor code.

I have a 1997 Mercury Villager with many miles. We get poor gas mileage. The check engine light is on. I want to replace the 02 sensor but cannot locate it on the engine. Is there a link with photo of physical location of the sensor and what are the steps to replace it?

I have seen some people finding a short near the PCM, some have quoted as to fixing the short and the P0135 Code disappears.

PCM=Power-Train Control Module

The knock sensor will run you about $350, look for the short first, maybe a wire got pinched or something, may be cheaper then diving into the knock sensor if it is not that.

I have also seen people replacing the knock sensor as them code do appear at the same time.

if its a 4 cylinder it will the 02 sensor closest or if not in the exhaust manifold

bad cat converter?

go to this website where there are files that will help you diagnose your issue.

http://autos.groups.yahoo.com/group/villagerquest/

P0135 is for heater circuit portion of the oxygen sensor circuit, not the sensor itself. It would just mean it's not heating the sensor so it will just delay the sensor controlling fuel trim until a few minutes later.

This code refers to the front oxygen sensor on Bank 1. The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. It the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0135.
Repair short or open or high resistance in wiring harness or harness connectors.
Since you have already changed out your O2 sensor (as long as you used to OEM replacement and not the "Universal" replacement) you should not have to replace it again. You might check your thermostat to part of the time it takes for the O2 sensor to start switching being based on coolant temp, if your thermostat is not operating properly, it could cause the coolant temp to take longer than what is considered by the ECM to be normal.

You have a broken wire at the connector for the 02 sensor. the brake may be inside the shielding.