Hi, I have a P0327 code intermittently turn on the engine check light. When I say intermittently, I mean every day, but if I reset it, its stays off for hours, then might come on when I restart, or less often juts whn it feels like it.
So, I have replaced both sensors with new items. No difference. So I checked the wiring from the sensor plugs near the thermostat housing and the ecu. Couldn’t get a fail unless I really gove the loom an earthquake size shaking. And yet it still fails.
Some observations… I dont get a limp mode or restricted performance…ever… Also, when looking at the wiring and the ecu I did notice some rubber type goo at the bottom of the 3 pins in the ecu that manage the knock sensors. Dont believe in coincidences and given this is the only place I have seen it I am guessing it has something to do with it, but I cant fathom a guess as to what it is. There is nothing like it in the area, although I dont know whats inside the ecu. Could it have come from there?
So, I am thinking one of 2 possible causes.
A failure in the signal wire (despite my testing). I dont thinks its the common signal wire since it also does the other knock sensor and a few others and I dont get a failure there.
a failed ecu? I dont get any other ecu type symptoms although I have had my cooling fans going mad lately. Assumed it was the relay control unit. Have replaced but not tested to any great degree…yet…
Any ideas would be greatly appreciated.
PS. Car is a 97 US spec XK8, converted to RHD for Australia.
P0327 is specific to the A bank and it is an out of range low error. According the JLR’s updated OBD codes, this is when the input level from the sensor is less than 1.25 volts. The MIL is only lit after two drive cycles failure but after the first drive cycle the ECM will set the timing to maximum retard. Suggests an intermittent loss of output from the sensor.
Fault finding will depend on what diagnostic equipment you have. If you can monitor live data and you can view the knock sensor output you could see if that disappears from time to time. I checked my Autel scanner which does live data but I couldn’t find KS on it. When I get a few mins. I’ll see if it’s on IDS.
If you don’t have the diagnostic kit, maybe you could run a separate cable from the A bank KS to the ECM Looks like it’s the slate coloured wire on pin 18 of connector EM13. It’s a screened cable. Haven’t tried this but can you cross plug the A & B banks sensors and see if the fault code changes?
It’s a bit concerning that you say the cooling fans are running a lot. With the engine cold, do you see in the swirl in the expansion tank with the cap removed when you blip the throttle? This is a good indication of the health of the water pump.
Haven’t got any further suggestions at present except a Google search on the fault code suggests that the fault code might be indicating a problem elsewhere and there are various undocumented suggestions.
BTW, I am quite amazed that it was worth doing a left hand to right hand drive conversion on an XK8. Apart from the obvious things that need to be changed, several of the modules change sides so the main harnesses have either had to be replaced or heavily modified. Is there a clue in that?
An update… after some reading it seemed that Thermostats might cause the fans to run crazy. So I put in a new one. easy job… then I checked the old one using a pot of water on the stove and a thermometer. No problems with the old one. Hmm.
Anyway, took the car for a drive… about 60 miles… now the fans run ALL the time… only shut down when I turn the ignition off… and even then after their own little last gasp at full roar.
I am 100% sure the car is not overheating. Even drove it 20 miles with the relay removed to stop the fans… no change in the temperature on the gauge and no change using my infrared thermometer. Now I know the internal gauge is an idiot light in disguise so I checked everything a few times over… No problems at all… except of course the fan having a heart attack…and I did see one occurrence of a P0332 which is the other Knock Sensor… so thats both having little tantrums.
So in my desk research on JTIS I found the following…
FAN RH signal to ECU is on pin EMS13-15
FAN LH signal to ECU is on pin EMS13-16
KS(A) signal to ECU is on pin EMS 13-17 and
KS(B) signal to ECU is on pin EMS 13-18.
So, I dont believe in coincidence so I am now thinking an ECU problem.
I have discovered that the fans will run with the ECT (Temperature sendor) disconnected, but that really proves nothing becase I’d think that the ECU would tell the fans to run if it thought the ECT had disappeared for some reason. The fans do not run at all with EM13 plug disconnected, so they must be getting earth all the time form the ECU. I will test this out tomorrow. If its true, then I am strongly of the view the ECU has a problem.
It might be worth checking the Engine Coolant Temperature sensor first. If you don’t have a spare to hand here are some resistance readings assuming an AJ26 engine (the AJ27 is different).
Cold ( 20 deg C) 1.7k ohms
1/4 470 ohms
Normal (fans just on slow) 250 ohms
You may be right that it’s an ECM problem. I don’t think the early 97/98 ECMs were particularly reliable. Mine keeps forgetting its key programming and then it won’t crank until I re-programme one of the keys. At least you won’t have that trouble because I think US spec. cars didn’t have the immobiliser but even so, if you do replace the ECM it may still need re-programming to sync it with Body Processor Module.
BTW if the ECM detects a fault with the ECT sensor it uses the data from the transmission oil temperature.
had the ECU checked over and some repairs done. Fans seem to be behaving properly now.
Still tracking down knock sensor errors. They have changed since the repairs, so now I will look at pulling apart the loom in the engine bay and probably replacing both sense wires, There ar some signs of heat damage to the extra coatings I put on the loom in that area. Keep in mind mine is a LHD drive looam that I bent and twisted to refir RHD, so its a bit ugly in terms of fit.
ECU problems. Some earth circuits had burned out and a few other suspect things. Got these repaired by a specialist.
Signal earth for both Knock Sensors was failing at the ECU connector plug EM13. Wiring fine, ECU fine (after repairs). Fixed the pin itself then all good.
So, I have 2 new Knock sensors, a new cooling fan relay, new temp sensor and new thermostat… all for nought… good news is I now have spares!!!
A bit of a long shot (since posted the last message in Aug 2018) but do you still have the spare knock sensors? If you do, can I buy one? One of my '99 XK8 is cracked (and seems tot cause a P0328 code).