When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello guys. Had a P0174 bank 2 too lean code a week or so ago. Mechanic said he changed out all 3 coils in the rear cylinder banks. Just picked up the car. Next day. Same code again !! He’s a competent mechanic. Just askin u guys before I bring my car back to him. Thx in advance
Last edited by NYCJAG2006; May 31, 2022 at 03:31 PM.
NYCJag, whenever you see P0171 or P0174, you should always verify that the big 3 are good (ie, PCV hose, brake booster line, and the IMT valve o-rings). In your case, I would venture that our IMT valve o-ring is your source of vacuum leak. If those are all good, it would appear that your mechanic put a new set of upper o-rings in, but did he do the lowers? That would be my next suspicion.
If it's not one of the "big 3" vacuum leaks, this is the next culprit. Curious he changed coils etc. For a p0174 code which MOST times is a vacuum leak.
Wouldn't those normally throw both codes (P0174 and P0171?) or do they sometimes just throw one of them? In any case I had both codes again last week after chasing them down a few months ago, the very first thing I checked was to pull the fuel purge line from the intake (just like the brake booster line in how it connects to the intake manifold) and saw that the tiny O-ring inside was broken whereas it was fine the last time around. Replaced that O-ring and sure enough that solved it, the check engine light turned itself off after five drive cycles. Those rings get brittle from the heat.
And per Thermo's second suggestion, last time I had those codes, it was in fact the lower gaskets. They aren't very difficult to get to if you're already at the rear coils, maybe another 10-15 minutes working slowly but it seems nobody seems to replace them until forced to.
I had a P0174 code a few months ago. My mechanic changed out the 3 rear coils first. Drove the car home same problem same code. A week later I get the P0174 and P0171. Bring it back. Mechanic changed out the 2 lower intake manifolds. Drive the car home. Service engine light comes on again !!! Same 2 codes. Please help. Thx.
Man. This is driving me crazy. Still have the P0174 code. Changed upper and lower intake manifolds. Sea foam clean. Throttle body cleaned. Plugs changed. God knows what else. Checked imt o rings. Look fine. Smoke tested. See no smoke. I’m thinking of changing out the big 3 when it comes to this code. Not sure what to do now. Any help is greatly appreciated.
Thermo do you agree with Dells idea it could be the maf sensor ? I don’t want to just keep throwing parts and money at my cat and still have that damn P0174 code. Thx for any help
NYC, I would say to clean it, but the MAF sensor should be causing a P0101 code, not a vacuum code. I am digging deep in my memory here, but there is also a vacuum line that runs from under the throttlebody to the back of the engine (between the engine and the firewall). i would look at that line. It is a hard plastic line that can crack, leading to a random vacuum leak. That would be my next check. After that, gotta take a step back, open up a cigar and blow the smoke into the engine bay and see if you can spot where the vacuum leak is. Because it is on bank 2, I would be looking at the connection where the brake booster line taps into the intake, the upper IMT valve or a leak on the o-rings for the intake on the cylinders nearest the radiator. Unless part of the plastic intake cracked, that is going to cover all of the likely suspects.
Dell and Thermo. My mechanic is tellin me it could be a faulty bank 2 0xygen sensor. I had a code P1626 in January and I bought a Denso sensor and he put it on and it fixed the problem. My question is could this existing P0174 code be thrown because of a faulty bank 2 upstream o2 sensor ? He wants me to get an oem sensor. It’s like $325. Don’t wanna blow that money if it’s for sure a leaking vacuum line. Gotta get this P0174 code gone for good. Thx for any help.
P1626 Jaguar Theft Deterrent Fuel Enable Signal Not Received/ B+ Supply To VCRM A/C Circuit Malfunction
P1626 Jaguar Theft Deterrent Fuel Enable Signal Not Received/ B+ Supply To VCRM A/C Circuit Malfunction.
Why would your mechanic replace an O2 sensor for that code?
P1647 is upstream oxygen sensor (#1) on bank 2. It is in the front of the engine.
P0057 is downstream oxygen sensor (#2) on bank 2.
P1646 is upstream oxygen sensor (#1) on bank 1. It is on the firewall side
P0037 is downstream oxygen sensor (#2) on bank 1.
As for can a bad or failing O2 sensor throw a different code, Denso website mentions a possibility (although low) of a RICH code not a lean code being thrown.
NYC, if I remember right, Denso is the OEM manufacturer of the O2 sensors for the X-Type. So, you did install an "OEM" sensor. So, I do not see a reason to replace the O2 sensor.
Something that is hitting me at the moment, I do not see any mention of checking the intake tube for a crack on the accordian section. That has been known to cause a vacuum code to pop up. The other thing that I would be questioning based on the work you have done is the o-ring between the throttlebody and the intake. IT is possible that this o-ring has cracked and it is leaking by now. I would believe these before the O2 sensor.
Ok. This past Saturday I fiddled around my engine bay ,trying to find the P0174 vacuum leak. Pulled off a few hoses. Checked the pcv valve. Etc. couldn’t find the vacuum leak. Cleared the code just to see if anything would change. Check engine light or any codes did not come back for several days and starts. Today I get the check engine light. Check it with my scanner. There’s no P0174 code anymore !!!! But I have an O2 sensor code. P2A04. O2 sensor circuit range/performance. Bank 2. Sensor 2. Please let me know if this is up or downstream sensor. Or a part number please. Thx for your help.
The generic definition of P2A04 (P0057) is the bank 2 sensor 2. That would be the downstream sensor (after the catalytic convertor) on the engine bank closest to the radiator.
That P2A04 code is not the code format listed in the Jaguar X-Type error codes. Might be the make/model of the code reader being used is referring back to a different code table.
However looking up generic OBD11 codes online it would appear to be referencing the Bank 2, sensor 2 not providing correct signal. Meaning the downstream (Post Cat) O2 sensor in the front bank nearest radiator.
In Jaguar codes you would be expecting Bank 2 downstream sensor issues to throw P0157, P0158 or P0160 codes depending on what the ECM is detecting as the parameter not being met by the O2 sensor.
Likely the sensor is bad, there could be a broken or shorted wire or shielding braid to the sensor (most likely still part of the sensor assembly anyway), a bad plug connection to the sensor, or an exhaust leak skewing the readings the sensor can detect.
An exhaust leak you would expect to hear easily, so unless both you and you mechanic have sustained catastrophic hearing damage (I truly hope not) you could probably exclude that from your list of culprits.
Hello guys. Can anyone give me a definite oem part number for bank 2 upstream o2 sensor please. Getting different part numbers. Not sure which is the correct one. Thx
Same code after repair. Help please
