ML320 CDI - fault codes and glow plug lamp
Discussion
Our 2008 ML320 CDI Sport has started keeping the glow plug lamp lit up for a minute or so after engine startup, even after waiting for the plug to go out initially. I scanned the car for fault codes, hoping to see something telling me that one of the plugs was on the way out but only saw two other codes which are:
P2133 - Throttle/Pedal Position Sensor/Switch F Circuit High Input
P2616 - Camshaft Position Signal Output Circuit High
Not sure if these things are connected to the glow plug lamp at all, I saw the latter code last year and the advice I found online was to change that camshaft position sensor, I did that and the code didn't reappear for ages, I stopped checking for codes so regularly after a while though so I can't say if the timing of those does coincide with the glow plug lamp appearing.
Any suggestions?
P2133 - Throttle/Pedal Position Sensor/Switch F Circuit High Input
P2616 - Camshaft Position Signal Output Circuit High
Not sure if these things are connected to the glow plug lamp at all, I saw the latter code last year and the advice I found online was to change that camshaft position sensor, I did that and the code didn't reappear for ages, I stopped checking for codes so regularly after a while though so I can't say if the timing of those does coincide with the glow plug lamp appearing.
Any suggestions?
Thanks chaps, useful info. I think I've found the video mentioned - https://www.youtube.com/watch?v=gdT2ChsbKAo
If there was a hardware issue with the plugs or the controller then should I not expect to see a specific code for those, as suggested in the video? One thing I forgot to mention is that the car does seem to have to crank a fairly long time to start from cold, even if we wait a good moment or so after the glow plug light goes out after switching the electrics on, but it's not every time.
If there was a hardware issue with the plugs or the controller then should I not expect to see a specific code for those, as suggested in the video? One thing I forgot to mention is that the car does seem to have to crank a fairly long time to start from cold, even if we wait a good moment or so after the glow plug light goes out after switching the electrics on, but it's not every time.
Again, thanks all.
The slow starting has been going on for a while, certainly since last winter. I put it down to us (my wife usually) not waiting until the glow plug light went out before starting the engine but it started doing it even if we wait a couple of minutes when the car is started first time that day. I had read that slow starting was a potential symptom of the failing camshaft position sensor so tried that since we saw the code for it anyway but the code went away for some time but the slow starts sometimes persisted.
The car has done 70k miles and is ten years old now - this is the first diesel we've had, are glow plugs normally an occasional service item, like spark plugs on a petrol, or is it just "change when one fails"?
The slow starting has been going on for a while, certainly since last winter. I put it down to us (my wife usually) not waiting until the glow plug light went out before starting the engine but it started doing it even if we wait a couple of minutes when the car is started first time that day. I had read that slow starting was a potential symptom of the failing camshaft position sensor so tried that since we saw the code for it anyway but the code went away for some time but the slow starts sometimes persisted.
The car has done 70k miles and is ten years old now - this is the first diesel we've had, are glow plugs normally an occasional service item, like spark plugs on a petrol, or is it just "change when one fails"?
Aha ok, so it's fairly generic/universal then? Not a Merc or M-class specific thing really?
So I checked the car again for fault codes at the weekend and the one about the camshaft position sensor (P2616) has vanished but I now see two codes related to the throttle pedal/position sensor, P2133 and P2137. The car had a good motorway run at the weekend and seems to have started better since then. I know from my own Jaguar that when codes start coming and going or other odd electrical sort of issues appear the usual suspect is a tired battery. Our Merc is almost ten years old now, we've had it for just over four and as far as I know it'll still be the original battery. Are these things also susceptible to battery-related gremlins?
So I checked the car again for fault codes at the weekend and the one about the camshaft position sensor (P2616) has vanished but I now see two codes related to the throttle pedal/position sensor, P2133 and P2137. The car had a good motorway run at the weekend and seems to have started better since then. I know from my own Jaguar that when codes start coming and going or other odd electrical sort of issues appear the usual suspect is a tired battery. Our Merc is almost ten years old now, we've had it for just over four and as far as I know it'll still be the original battery. Are these things also susceptible to battery-related gremlins?
Finally got round to doing something about this, got hold of a glow plug module (made by Beru) and changed it out last night. The glow plug light still comes on just after engine startup. Checked codes, I have P2133, P2177 (relating to Throttle/Pedal Position Sensor issues) and P2616 "Camshaft Position Signal Output Circuit High", nothing that specifically mentions glow plugs. Cleared them at the time, will recheck later.
Any suggestion as to where to go from here?
Any suggestion as to where to go from here?
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