I have a 2004 X-Type 3.0 with the check engine light and a P0174 code (System Too Lean - Bank 2). The vehicle has 85,000 miles.

My gas mileage is good (around 18 city). The engine runs well and there is no noticeable miss in the idle. Occasionally the engine will stumble significantly during acceleration but that doesnt happen very often.

I did the poor mans smoke test. (plugging off the air intake before the MAF and blowing smoke into the intake. I did not find any vacuum leaks. I also sprayed the area with carb cleaner while listening for a change in engine revolutions and found nothing. I also cleaned the MAF sensor.

If I understand correctly bank 2 is located at the front of the motor (closest to radiator).

Given that I have only the P0174 code it would seem the issue is confined to the front cylinders. Now the question is "How I do I pinpoint the issue?"

(I also have ABS codes but that should be entirely unrelated)

I recently purchased this vehicle and I have no information on previous tuneup history. I dont know if the spark plugs, fuel injectors, intake manifold gaskets, or IMT gaskets have been replaced.

Any help would be greatly appreciated.

 

Since your engine runs well, and Bank 1 is not throwing a lean code P0171, my gut says to replace the Bank 2 upstream sensor. It contains an electric heating element that fails with age. At 85K miles, you're about at that point.

The Bosch part # is 15627. The Denso part # is 234-9029. Make sure you buy the Upstream sensor, not the Downstream sensor.

Here's the Bosch part on Amazon:

And the Denso part:

These upstream sensors are also called Oxygen (O2) sensors, Air / Fuel sensors and Lambda sensors. They measure the exhaust gas so the ECM knows how to adjust the gasoline flow thru the fuel injectors.

To remove and install this sensor, you'll need a special socket with a slot for the sensor's wires, like this:


Most auto parts stores lend these for free, with a small deposit.

To locate the Bank 2 upstream sensor (yes, Bank 2 is the radiator side of the engine), look down between the battery and behind the headlights for two electrical connectors, one grey, one black, mounted on a bracket on the front-side of the battery. The grey plug is for the upstream Bank 2 sensor, the black for the downstream sensor. Unplug the grey connector and follow the wire to the upstream Bank 2 sensor.

To reach the sensor, you'll need to remove the battery and air filter box. Below the air filter box you'll see a horizontal, plastic pipe with a descending T in it. Be careful not to exert pressure on this pipe when changing the sensor, as some members have accidently cracked the lower leg of this pipe where it bolts to the engine block, causing a coolant leak.

Another possible reason for your P0174 code is a small vacuum leak in the intake manifold. Likely culprits are the IMT O-rings, a crack in the underside of the PCV hose (particularly the old-style smooth PCV hose), and the check valve in the brake vacuum line. There are numerous threads on how to check and change these.

But my gut says the issue is the Bank 2 upstream sensor, because the engine runs well, Bank 1 is not throwing a lean code P0171, and 80-110K miles seems to be when the heating element fails in these upstream sensors.

Please keep us posted on what you find.

 

Given that my code is only pointing to an issue with bank 2 I agree that most of the likely issues (bad IMT gaskets, vacuum hoses, etc...) are not the issue. I did get a P0171 code once........but it never came back. The P0174 is almost always on or pending.

What about the upper and lower intake gaskets? Are they prone to needing replacement on Jaguar X-Type? (My vehicle only has 85K miles) I suppose a clogged fuel injector could also be causing the issue. I think I can check the fuel trim per port with my OBSII tester. Perhaps that will give me a better idea assuming the issue is relatively consistent. Yesterday the check engine light went out while driving(it cleared its own code) for a short while. And then a few miles later the CEL came on again. :-(

Now I might have a different issue that is possibly related. I noticed fluid puddled near the coils on bank 2. I dont know yet if it is oil or coolant......I really just need to remove the airbox to take a closer look.

 

Med students are taught: "When you hear hooves, think horses, not zebras."

Let's first address common causes for a P0174 error code (lean bank 2). The culprit could be a leak in the upper or lower intake gasket, but first focus on the common causes that are also much easier to fix:

1) Replace the Bank 2 upstream oxygen sensor
2) Check for and fix any vacuum leaks around the IMT O-rings, PCV hose and brake booster line check valve.

If the P0174 error code comes back after you address these common problems, then I'd suspect a possible fuel issue, e.g., a partially clogged fuel injector, for which we can discuss relatively simple remedies.

The upper or lower intake gaskets are typically changed only when you have another reason to remove the intake, e.g., replace spark plugs or a leaking valve cover gasket on bank 1 (the firewall side).

I wouldn't worry about the P0171 code (Bank 1 lean condition) that appeared once and never came back. However, if replacing the Bank 2 upstream O2 sensor clears your P0174 code, then don't be surprised if the Bank 1 upstream O2 sensor throws a P0171 code and needs to be replaced in the next 10-20K miles. Not to worry - it's somewhat more accessible than the Bank 2 sensor.

The fluid puddled near the bank 2 coils could be a simple as spillage during a sloppy oil change by the former owner. I'd clean it up, including anything in the spark plug wells, where it could cause the coils to misfire thru the liquid instead of thru the spark plugs. Since you don't have any error codes for coil misfires, and the engine runs well, that's probably not happening, but I'd clean up any fluid in the wells to prevent future issues. You'll have better access to the bank 2 coils when you remove the air filter box to change the bank 2 upstream O2 sensor. After it's cleaned up, monitor the area for any new accumulation, and just as a precaution, keep an eye on the fluid levels until you understand this one.

 

If you only have P0174 on Bank 2, that means your upper or lower intake manifold gasket blown away on cylinder 04. There are chances you will find black burnt carbon on intake manifold underneath.

 

3+ yr old thread. Forget it.

 

Very good explanation regarding to the P0174 code.
I want to take opportunity and to ask you for some codes which comes to my Jaguar X-Type 3.0 Gas 2003 (100k Miles).
B2614
P1582
P0174
P2503
P0302
P1314

Please can you give your explanation regarding those codes.

 

@ AdriaJAG

Answered in your duplicated request in the other thread.