Hi all,

As if I've not been dealing with enough issues with my car lately, I've now just had my car throw fault code p0121. The RPM's bounced around between about 1100 RPM and about 2500 RPM and was running really rough with no power at all. It would not accelerate from the pedal but was juddery and lurching. It also threw DTC Unavailable, Engine System Fault and Parking Brake Fault.

I decided to replace the throttle position sensor after doing some research on that fault code.

So I disconnected the battery, removed the throttle body and replaced the throttle position sensor with a new one.

I marked around the position of the old sensor and installed the new one in pretty much the same place.

Refitted the throttle body, reconnected the battery and turned the ignition key on.

The car immediately threw the same messages on the display. This time though the fault code is P0222.

The revs don't go any lower than about 1200 RPM and the car is running rough.

Is there a calibration process that I have to do. I found a thread on here for a procedure to replace the TPS but I tried following the process to re-calibrate it but it still does it and still throws the same P0222 code.

I've tried to measure the voltages by back probing.

I'm not sure what voltages I should be getting.

I've worked out the following pins so far:

Orange - Constant Voltage of 4.98 Volts when connected to ground of car body
Red - Reads 0.79 Volts when connected to Black/Green ground wire - If I move the sensor on its axis then the lowest I get is about 0.65 Volts and goes over 1 Volt if turned in the opposite direction.
Yellow - Reads 0 Volts when connected to Black/Green ground wire
Black/Green - Ground

Does anyone know what voltages I should be seeing on these wires?

And what are the correct voltage ranges for each wire so I can check that the voltages are in the correct range when throttle is at idle and wide open?

Does P0222 relate to the 0 Volts on the Yellow wire?

Thanks,

Chris

 

Here is a good summary of the fault code:

https://www.fixdapp.com/blog/p0122-m...symptoms-fixes

Strange that you have not got RP.

Which TP have you fitted?

Denso?

There is a procedure for fitting the TPS (where are you Brutal) but I am guessing that the way that you have fitted it is good enough.

 

Hi Chris,

You can download the Jaguar Powertrain DTC Summaries here:

Jaguar X350 Powertrain DTC Summaries 2003.5

Here are the definition and possible causes of P0222, which you mention in the title and at the end of your post:



Here's P0121 which you also mention:



Both suggest that common causes are problems with the wiring or electrical connector, so it would be worth checking those carefully before condemning the sensor.

Cheers,

Don

 

Hi guys,

Thanks for all the help so far.

This is a really odd problem. It looks like I'm getting 0 volts from the yellow wire when back probed so I think that is the problem.

I have tested the Ohms of the old TPS sensor that I removed from the car.

There does not seem to be any dead spots over the range. I'm going to remove the new one from the car and compare. Just to rule out the sensors themselves.

I do think I have some issue with the wiring harness or the plug possibly. Is there some kind of relay controlling the voltages to the TPS Sensor?

My Ohm readings on the old sensor are as follows:

Orange - Constant 200 Ohms when connected to B/G or ground - even when sensor is moved through it's range.
Red - When connected to B/G wire I get 5 Ohms closed up to 201 Ohms when fully open. The Ohms change smoothly when moving through the range.
Yellow - When connected to B/G wire I get 87 Ohms closed up to 211 Ohms when fully open. The Ohms change smoothly when moving through the range as well.
Black/Green - Ground

Just got to also now find what the acceptable resistance is to make sure these resistance readings are acceptable.

Thanks,

Chris

 

I am no expert but it looks like you need to check the yellow for continuity between the TPS and the ECU.

There are no connectors on that wire and it is screened to earth.

 

Thanks meirion1. I've been going through the workshop manual to see where that wire goes and comes from. It has some diagnostic procedures to check for ground, volts and resistance to follow which I will do at the weekend or sooner if I can. I'm also going to check the resistance on the new sensor just in case and compare it to the old one.

 

Hi all,

I got around to looking at this today.

I was going to start testing the wiring harness and go through all the TPS diagnostic procedures that are mentioned in the workshop manual.

Then I had a thought. I removed the new sensor from the car and tested it for resistance on all the pins to ground first, just in case I got sent a rubbish sensor.

So I stuck it on the multimeter and tested for ohms on the yellow to black/green (ground) wire on the new sensor whilst removed from the car as that was the one with 0 volts.

Guess what - the damn thing had no ohms (open circuit). Tested the whole range from closed to open and nothing. The red to black/green (ground) had ohms and so did the orange to black/green so those were working ok. But just the yellow to ground was nothing so there must be a fault in the new sensor internally.

I compared this to the old sensor and the old sensor had ohms readings right across the range from closed to open on the yellow to black/green.

So my new sensor is actually faulty and hence caused the car to get no volts or signal back to the ecu from the sensor on that part of the TPS circuit. Thus causing the P0222 fault code and the really rough running. It'll be going back to the supplier for a refund.

I then had a dilemma. Wait to get another new one or see what happens when I put the old one back in the car as the resistance across the old sensor appeared to work right across the closed to open range on each wire.

I couldn't wait for a replacement sensor as I need to use the car for work on Monday. I decided to refit the old sensor and see what happens.

Luckily I've marked on the throttle body the position the old sensor was fitted in before I removed it.

There is a guide that I found on the reset procedure to follow when a new TPS is fitted. I followed that guide and the car actually drives much better than before and I took the car for a 2 hour drive with no faults. I didn't even get the P0121 or P0222 fault again. So I have no idea why the car originally kept throwing the P0121 codes. It's not doing it now at all.

However, as I got home and let the car idle for a few minutes, just to be sure all was ok, and whilst I got some shopping in it threw fault code P0175 and P0172. It didn't run rough at all though. I wonder if the TPS I refitted just needs to be moved slightly. I'm wondering if I fitted it slightly off it's old position. I checked the RPM at idle and it's higher than it was before I removed the sensor. It's running about 15 RPM higher than before.

Thanks for all your help with this.

Cheers.

Chris

 

Still trying to get to the bottom of these fault codes of a rich system. I've noticed that it appears to throw the code P0175 and P0172 when the car has been idling for a few minutes.

I've noticed that I can clear the fault and drive the car for over an hour without it throwing the faults. As soon as I stop completely and idle then it throws the codes.

I've monitored live data and I can see that my short term fuel trims on both banks drop to -18 and lower as soon as I take my foot off the throttle and it begins to lower the revs towards idle speed. After a few seconds the fuel trim comes back to about -3 and it then appears to throw the rich codes.

Just got to figure out why now.

Thanks,

Chris

 

I've now also changed my thermostat housing that I found to be badly leaking incase the rich codes where being thrown because of a bad or faulty coolant temp sensor. That and the thermostat was part of the new housing so it was replaced at the same time. I changed the water pump at the same time as well just in case and because I had a spare ready to install at some point soon so decided to change that whilst I had the coolant emptied and whilst I had room to get the old one out.

My coolant temp is now a bit lower (approx 3 or 4 C lower) than before but the car is still throwing these rich codes so I don't think it can be the coolant temp sensor now either.

I'm also going to test the MAF in case it's that.

Thanks,

Chris

 

Well I'm not sure if I have a problem with my MAF sensor as I'm not sure what the correct readings should be and don't have anything to compare them to.

I've done the workshop manual tests for the MAF and they where all successful. But at idle the MAF readings seem to fluctuate quite a lot and that fluctuation also occurs at the same time as the changes in RPM at idle. So I'm not sure if the MAF is causing the RPM changes or if something else is changing the RPM and then the MAF changes it's readings as a result.

The rich codes have now stopped appearing but my car now keeps throwing 'Restricted Performance' with no fault codes as soon as I start the car. The car idles really rough and now keeps stalling when you try to start it.

This is now getting really frustrating tracking down the cause of these problems. I'm unfortunately now getting to the point where I'm thinking of getting rid of the car as all the problems I've had so far just is getting too much work which I just don't have the time to sort out.

Thanks,

Chris

 

Stalling at low revs can be lack of fuel e.g. blocked fuel filter or an air leak - look at idle fuel trims if it runs long enough to read them.

 

I suggest that you clean the MAF first.

https://www.obd-codes.com/p0172

 

Hi Chris,

Off the top of my head, I think you should see something in the range of 4 to 6 grams-per-second from the MAFS at idle, and 30, 40 and more when the engine is revved. It seems like I've seen some typical specs somewhere, maybe in one of the Engine Management System manuals.

Cheers,

Don

 

Hi Don,

Much appreciated. I've started a new thread on the MAF readings I'm getting. I suspect my MAF is just not working properly. I think my readings are much lower than they should be. I'm sure it's either dirty or faulty.

Thanks,

Chris

 

wonder if you'd be able to tell me what the reset procedure is following a tps change? I've had a quick Google, and can't find anything
thanks