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I have found conflicting info on where the sensor is located.
(2003 X-Type 3.0).
It appears one sensor is staring at me and quite easy to get to. It is located pretty much right under the electrical connectors on the firewall.
There appears to be ANOTHER sensor that is sandwiched between the firewall on the BACK of the engine (I hope this is not it, as it looks like a PITA to get to!).
So, WHICH sensor is which?
I know the code refers to Bank 1 (upstream), Sensor1, just not sure which sensor that actually is....
Coralking, Bank 1 is the side of the engine up against the firewall. The Sensor 1 is the upstream sensor. So, that will be the one sticking out the side of the large can just as the exhaust exits the engine.
As for accessing this sensor, not as bad as you might imagine. Granted, you will need to remove the intake manifold to give yourself some room. But, with it off, you should have plenty of room to do what you need.
Thermo, I changed both of my o2 sensors by the firewall without removing the manifold. It's a little tricky but with the right tools it's fairly easy and a lot less work.
To ensure you have the correct sensor, follow the wires.....
On the firewall, by the brake master cylinder are two electrical connectors, one grey, one black. Unplug the grey connector and follow the wire to the Upstream O2 sensor for Bank 1 (the firewall side). The black connector wire goes to Bank 1's Downstream sensor.
For Bank 2 (the radiator side), the grey and black connectors are on the front-side of the battery, behind the headlights. Same logic: grey connector is the Upstream O2 sensor for Bank 2, the black connector is Downstream sensor.
JC: I'm not aware of any valve cover videos, but after you remove the intake manifold and coils to install new spark plugs, it's rather straight forward and minimal effort to replace valve cover gaskets.
Each valve cover is held down by 12 & 13 small bolts, see attached pictures. A few of bolts also double as mounting points for: (a) intake manifold bracket, (b) coolant hose, (c) wiring harnesses, (d) engine cowling bracket, etc. Just keep track of what goes where, and take a few pictures as you go.
Disconnect two electrical connectors, one atop each valve cover near the serpentine belt. They're for the variable camshaft timing (VCT) solenoids - see picture.
Now pull each valve covers straight up. Each cover has a ~1" diameter hole encircling the VCT solenoid, so pull straight up until the cover clears the solenoid.
The old gasket will likely cling to the head where the factory or last mechanic used RTV silicone for a better seal. Clean off the old sealant, and apply a new bead in the same spots, particularly where the front gasket makes sharp bends over the camshaft, near the water pump.
Torque the valve cover bolts to 10 Nm in the order shown. 10 Nm is only 7.4 ft-lbs, so go easy.
Thanks dwclapp, good info! I have just replaced the cam cover gaskets, coils, and plugs and manifold gaskets. Since this is an DOHC engine, I'm calling them cam covers. The valves are actually down those scary holes in the lower intake manifold.
This repair/maintenance was prompted by engine stalling, misfires, and a bad sulfur smell at the tailpipes. I did find oil in the spark plug well in the rear bank. One plug came out dripping with oil, Lol. Anyway, I got it all back together and it started but still ran poopy. I have codes: P0172, P0175, and P0101.
I believe the P0101 is MAF sensor code, but my MAF is only a year old and looks to be fine. The other two codes are rich in both banks. I think the MAF and O2 sensors are not jiving, or giving the ECM conflicting info about the amount of air and oxygen going thru the engine.
On the 02 sensors, is it the heaters that fail? In a youtube video I got that the resistance across the heater wires should be near 1 Ohm. Is that correct?
I measured the front bank sensors with the engine cold and off, one heater reads a single Ohm of resistance, the other reads 6 Ohms.
The other two wires (signal and ground) have to be measured with the car idling, right?
Patterson: "Valve" vs. "cam" covers at first confused me because the covers are over the cams, which are over the valves. Then I realized the intake valves are also visible thru those "scary holes" in the lower intake manifold. It's just a matter or perspective: top or side view of the same valves.
I no longer test the voltage of oxygen sensors since the cost dropped to ~$20 (way down from $100+ not that long ago), the effort to replace them is much more than the cost, and they last ~100K miles, so expect to replace just once in the lifetime of most engines, assume old age and not a contaminant like silicone. When the check engine light is on at ~100K miles and the OBD code points to a bad oxygen sensor, I simply replace the bad one and wait for the others to fail soon afterwards.
Upstream O2 sensors usually go bad first because they have a heating element like a hot toaster wire. Soon after start-up, while the engine is cold, this heating element warms the upstream sensor for more accurate O2 readings. After the engine warms up, the heating element is superfluous. At ~100+K miles, the element burns out, causing an open circuit. Think bad filament in a "burned out" incandescent bulb.
O2 sensors, upstream and downstream, also go bad with age when they no longer generate 0-1 volts in response to the O2 content of exhaust gas. Too much O2 at the upstream sensor means a lean fuel mixture (less than 0.5V), and too little O2 means a rich mixture (greater than 0.5V). The EMC adjusts the fuel injectors accordingly, aka, adjusts the fuel trims.
Downstream O2 sensors confirm the catalytic converters are burning residual fuel, confirmed by a drop in O2 across the converter.
For your P0101, I'd clean the MAF with MAF cleaner, not carb cleaner. If that doesn't work, replace the MAF for ~$15. A bad MAF can cause the rich conditions in both banks (P0172 & P0175). Also replace the air filter if old or dusty driving - restricted air flow can cause a rich condition. I assume the engine is warming up properly - a cold engine runs rich, e.g., a broken thermostat.
Patterson: "Valve" vs. "cam" covers at first confused me because the covers are over the cams, which are over the valves. Then I realized the intake valves are also visible thru those "scary holes" in the lower intake manifold. It's just a matter or perspective: top or side view of the same valves.
Hey there thanks for the thoughtful response. I'd say cam cover is accurate because the first thing those covers are covering is cams!
You’re right about testing the sensors, I was going to get all into that, but what the hell, If the sensors are original, and so all the same age, they will all need to be replaced after 100K miles. I have 150K. The Jag was running great up until a few weeks ago. I bought the downstream oxygen sensors tonight on Amazon for $50 each. Denso 234-4798. I’ve seen the off brand $20 versions, I guess I’m falling for the Denso brand and spending more in hopes of a more reliable sensor.
Big thanks for all your info man! I just put the upper intake manifold back on after getting all the way down to the cam cover gaskets. However, I'll be removing it again to do the O2 sensors back there at the firewall. The gaskets are new-ish in that I did drive the car to work once with them in there, but I'm not buying new ones just so I can pull the manifold to reach the O2 sensors. I figure I'll go with left over gasket sealer I have from the cam cover R&R. So I'll just add gasket sealer to one side of the new-ish gaskets after replacing the sensors and put the upper intake back on to torque.
Do the heat shields get in the way when R&R-ing the O2 sensors? I bought the socket kit with the slot for the wire and two angled/offset adapters. These sensors have been in there for some 15 years! Will I need a breaker bar? Lol
Last year an Amazon vendor charged me only $20 for an NGK 25607 downstream O2 sensor. I was lucky, I guess, because today it's $73 from the same vendor. Fully agree that NGK/NTK, Denso and Bosch are worth a few extra $'s over "brand X".
It's unfortunate you didn't replaced the bank 1 / firewall O2 sensors when you had the upper intake and cam cover off the engine - access is so much easier. But you can replace these sensors now without removing the intake and cam cover - I've done it.
Stand by the right front tire and reach your left hand under the intake manifold, between the engine and firewall to slip the slotted socket over the O2 sensor. I had to bend the heat shield edge back a ~1/8 inch to clear space for the socket to slide onto the sensor. Also, unplug the sensor's electrical connector - on the firewall by the brake master cylinder - so the sensor wire can turn freely while you unscrew the sensor. Then snap the articulated socket wrench onto the socket and rotate the handle away from you, between the firewall and intake manifold, to unscrew the sensor. It does not take much torque to break the sensor free, and once it starts turning, you can remove the articulated socket wrench and unscrew the slotted socket and sensor with your fingers.
Reverse the process to install the new sensor...... screw it in with your fingers, and tighten it with the articulated socket wrench and slotted socket. Last, plug in the electrical connector.
It takes a little patience, but it's doable, and less work than removing the intake manifold and cam cover.
First question Mr. dwclapp, why does your ID pic look like a Prius lime bar? Do you still have the X Type?
In any case, thank you for all the pics you posted in your October 2014 post. Those were a big help today. I replaced all 4 oxygen sensors this weekend and put it all back together. I did re-remove the upper intake to reach the firewall sensors. I wanted to be able to reach and see the sensors without cussing up a storm, considering its Mother's Day and all.
The radiator side O2 sensors were much easier. The downstream is easy to approach from below if you raise the vehicle. For the upstream sensor I removed the air box and intake snorkels and the brackets & accessories to get my socket securely around it.
Getting your socket securely around the flats of the hex is very important. It's a 22mm wide nut at the waist of the O2 sensor that tells your fate. If you can not grab onto those metal flats and turn the body, you are funked. I almost stripped the firewall side downstream O2 sensor.
I found that the socket was too tall, so I tried the crows foot, and that almost stripped the corners off the hex. This sensor body was stuck in there, so I sprayed it with bolt Blaster and waited an hour. I actually sprayed it a couple times over the course of an hour and tapped on it with hammer while I sprayed more. I finally got it to release, but it looked like this, you can see that it was starting to strip the hex.
In any case, I replaced all 4 oxygen sensors with help from ppl like you that post pictures and instructions on the Jag forums. I had quotes for around $3K to do this job from several shops in town. I did it for $300 cash and my time.
I started the car up this evening and let it warm up a bit and drove it around the block. It idled well and drove nice in first gear. I didn't tax the Jag too much tonight. I'm re-using my upper intake manifold gaskets and throttle body gaskets.
Of course, the ECM is remembering the old trouble codes for now. With a good drive cycle, it should determine that this Jag is back in town. I'll say one thing, the exhaust does not smell like burnt firecrackers anymore.
Patterson: Yes, my daily driver is a 2002 X-Type Sport with ~142K miles, thanks in large part to suggestions and confidence gained from this forum.
"Prius lime bar"? LOL! It's a Lamborghini, not mine, that I saw in a parking lot and sent a pic to friends with the joke caption "My new ride!"
Bummer that one of your O2 sensors put up a fight. All 4 in my X-Type loosened without much resistance. A trick that's a day late to help you, but could help the next reader........
If an old O2 sensor is difficult to remove, cut off the wires at the sensor and use an ordinary 7/8", 6 point deep socket to loosen it. An ordinary 6 point socket is thinner, but grips better than the special slotted socket needed to install the new sensor.
Prius lime bar? Maybe the picture is so small that it doesn't do justice to a Lambo. Did your friends bite on this pic you sent? Lol.
One thing I learned, and I've known this forever. Make sure you have a good table next to the engine bay when doing this kind of work. You have to keep track of every bolt, clamp, and nut piece you remove. Plus the tools need to be in check. ...sockets, extensions, wrenches, screwdrivers, and pliers.
Having deep well sockets is important, and making sure that your sockets don't fit loose on the driver end, bc they can fall off when you have your wrench reaching down a cavern to catch a bolt head. I lost a nice 10mm deep well socket on this run. It fell behind the heat shields near the firewall when I was tightening the rear bank cam cover to torque. That screwed me up bc I had gasket sealer drying and no other matching socket to fit my torque wrench. I ended up tightening the rest of the rear cam cover by feel. I put my torque wrench in a vise and did a 'how does that torque feel?' test. And I guess I used muscle memory to finish. Lol.
The engine light has not turned itself off yet, but I have hopes that it will. The car runs great at idle and up to 3K RPMs, but it is still in limp mode. I could clear the codes, but better if the ECM does it on the natch!
Patterson: Congrats! It's satisfying to know 99.9% of your car was fine and you repaired the troublesome 0.1% for a fraction of just the sales tax you would have paid on a replacement car.
For ~$10-15, reward yourself with an ELM327 OBD2 code reader to reset the CEL and error codes. Search eBay for "ELM327". I used a Wifi ELM327, iPhone and free app called OBDCarDoctor. Others use a Bluetooth ELM327, Android phone and free app called Torque. Many free OBD apps are out there.
ELM327's read and clear OBD2 engine codes for every car you are likely to work on. They don't read Jaguar codes for ABS and SRS (supplemental restraint system, aka air bags) - for those I use an Autel AL619.
But for $10-15, an EML327 is invaluable to clear engine error codes after a repair and confirm you succeeded when the error codes don't return.
"Patterson: Congrats! It's satisfying to know 99.9% of your car was fine and you repaired the troublesome 0.1% for a fraction of just the sales tax you would have paid on a replacement car." True is that! I know I'm prettty close, but I read the codes tonight with BAFX OBDII reader that uses Torque on my Android.
My misfire P300 codes went away, and P0171 went away, but from scanning just now I have
P0172 & P0175 rich in both banks - these ones have been there since the trouble started a month ago, along with a MAF code, not sure which one.
P0101 - Mass Air Flow Sensor Circuit/Performance Malfunction
P0102 - Mass or Volume Air Flow Circuit Low Input
P0112 - Intake Air Temperature Circuit Low Input - New code.
Car drives in Limp mode to work and back, Lol. I'll try a new MAF tomorrow, but I replaced this MAF a year ago, and I took it out last week and it looks fine.
This has been on my mind: Some of the long screws that hold the air box together and sealed are stripped and don't apply any force to seal the air box. I mean, C'mon, they have steel screws tying into plastic. That's not going to last. A case of Inferior Engineering I say!
Maybe I'll seal the air box better and get a new MAF sensor.
10-21-2014 | 03:01 PM
P1646 - Bank1 Sensor1. Where is it?
Prius lime bar? Maybe the picture is so small that it doesn't do justice to a Lambo. Did your friends bite on this pic you sent? Lol.