Camshaft Position Sensor Fault codes check engine

[bill420e]

I already put a new camshaft sensor in and still the codes will not clear now. 4-8 17-6 16-13 & 22
Engine light is on and does not start great and runs very poorly.
I tested voltage on the wire going to the sensor and was not able to measure any voltage with the ignition on.
I do not see any wire damage.
Not sure what to look for next.

 

[gsxr]

You won't measure any voltage at the connector. Has the engine wire harness been replaced? If not, you'll need to do that first. What brand cam sensor was installed? OE is NLA. I've never seen one of these fail (yet).

Had you done any work prior to this, or did the engine suddenly start running poorly out of the blue?

How many miles, and is there any record of the timing chain rails/guides being replaced?

 

[bill420e]

I am not sure if the engine wire harness was replaced. I think it was. I had tested the resistance on the old sensor at 1200 ohm and the new one at 1000 ohm. The new sensor is Hella. The car has never had any major work, just sensors and new cats, motor mounts....it has 225k miles and was running great before this fault showed up. When I got the fault cleared a week ago, the car ran great then, but came back in a day. Now I can't clear the faults.
Actually, I was able to reset 17 and clear 17-6.
The car really did not show signed of wear in power and smoothness. What a great motor.

 

[bill420e]

I got the cat with 175k from a guy who found a nicer 420e and then sold this one to me. Not a looker, but a great driver most of the time.

 

[gsxr]

Click here to see how to verify the date code of your engine harness. If it's original... you'll need to replace it. An original harness can cause all sorts of weirdness.

To confirm, your car WAS running great, but is now running poorly and you have a persistent fault code for the cam sensor - correct?

With 225kmi, the chain guide rails are overdue for replacement, if they have never been done. There is a tiny chance that broken chain rails could have allowed the intake cam to skip a tooth or two, which could possibly cause the cam sensor code which won't clear. Unfortunately, you must pull both valve covers to check cam timing and visually inspect the chain rails. Replacing the chain rails is a DIY'able job, but very time consuming (plan on 10-20 hours if you've never done it before). Parts are cheap, it's just a lot of tedious labor, especially if you want to clean the engine while you're in there.

The timing chain and tensioner almost never need replacement, and the engine will last nearly forever if maintained properly, but those plastic rails succumb to heat and time.

 

[bill420e]

The tag was chewed up by vermin, but the wire looks newer than some in the area. There was damage to other wires that I repaired but no visual attacks on the wires going from the sensor or near the computer box.

The car was running great until the engine light came on. Then it ran great again after I was able to clear the faults. Now it funs crappy and I cannot clear the the faults.

I am sure I can do the rails. I have changed them in lots of other Mercedes and done work on my 500sl that I had with a m119. But, I am not thinking it is a jumped chain as it came back and ran great after I cleared the faults last time.

 

[R129 UK]

Are we talking CAMSHAFT or CRANKSHAFT sensors here?

 

[gsxr]

Camshaft sensor (CMP). The fault codes are also for cam sensor.

Check the wires at any fuel injector. Slice open the cover if necessary to see the colored wire inside. It should be bright colored insulation with NO cracks at all. Old harnesses will have dull colors and cracked badly, exposing the stranded copper wires.

Note that clearing codes will not cause the engine to run better, all it does is delete the stored code from the "memory" in the computer module. If the engine ran better after clearing codes, this was 100% coincidence.

 

[bill420e]

The wires are brightly colored and no cracks. It clearly looks like a new harness.

I had ASR faults in the past that put the car in limp mode. I thought maybe this was something similar.

Do you think it likely that the new sensor could be not great with a resistance of 1000 ohm? I thought it was supposed to be more like 400-800 ohm.

 

[gsxr]

The wires are brightly colored and no cracks. It clearly looks like a new harness.

OK - that is good news.

I had ASR faults in the past that put the car in limp mode. I thought maybe this was something similar.

Limp mode is cleared by turning the ignition off/on, but fault codes remain stored. I assume you have the limp mode fixed now (but, this would not be related to poor engine running).

Do you think it likely that the new sensor could be not great with a resistance of 1000 ohm? I thought it was supposed to be more like 400-800 ohm.

It's unlikely, but possible, that the replacement Hella China sensor is faulty or flaky. I don't recall what the normal resistance is, but measure the old one for comparison.

The crank sensor typically measures ~800 ohms or so when cold, and may read 800-1000 warm? Defective crank sensors cause the engine to die and not restart until cooled down, and the sensor will read open / infinite resistance when the engine won't start. Note this is not the same as the camshaft sensor being discussed here.

 

[bill420e]

Just a reminder this is the cam position sensor fault that we are dealing with.
I will check some wires for continuity.
It would seem to me that I should also be checking for voltage coming to the sensor.

 

[gsxr]

Just a reminder this is the cam position sensor fault that we are dealing with.
I will check some wires for continuity.
It would seem to me that I should also be checking for voltage coming to the sensor.

There is not necessarily voltage to be measured at the sensor. You'd need to compare to another car that is running normally.

 

[bill420e]

I checked the CPS wire for continuity and all good. I also unplugged and plugged back in the wire to the magnet for the cam. I started the car and it was running very rough and after a few revs the ASR light came on too. I checked faults
4 no fault
6-30
7-14
17-18
19-6,22
I reset faults codes and hard reset.
Car sounds great and no check engine or ASR.
I don't understand. I will check faults again after some driving.
Thank you so much for your information.
I suspect that the rails were replaced. The previous owner was a 500 420 enthusiast and master mechanic. The car has 175K and ran great. He has just found one with less miles and a great interior and body. Mine has paint bumper and interior issues. But, I paid $2k for it 6-7 years ago.

 

[gsxr]

6-30 - This is a "phantom" code that always shows after limp mode. Ignore this.
7-14 ="Closed throttle position switch (S29/3)" which can cause limp mode. More info here.
17-18 = "Magnets for CKP sensor (L5) not recognized" . If this code persists, try adding a 0.5mm shim under the crank sensor.
19-6 = "Idle speed control inoperative", related to ETA, E-GAS, or limp mode
19-22 = "Camshaft position sensor signal defective" - this is odd, since there was no CMP fault on pin #4 or pin #17.

A bad camshaft sensor should trigger code #8 on pin #4 (LH) and/or code #6 on pin #17 (EZL).

Use this document to translate the codes, if you aren't using it already. Make sure you are fully clearing all codes, and not seeing the same old code again.

 

[bill420e]

Update...drove the car yesterday and it drove great except for a few seconds where it kind of stalled and had no power. Codes show only one code 17-18 camshaft magnets not recognized. It drove great for the next 5 miles to home.

 

[bill420e]

Thank you for the great information. I will see if this persists and shim the sensor if it does and see if that helps.

The throttle linkage has sometimes stuck a bit. So hard to lubricate that one ball hidden in the intake manifold area. But I do my best spraying it and it loosens up and I don't get the fault and limp.

Should I buy another sensor of the brand you suggested?

 

[gsxr]

Cam position sensor 002-153-95-28 is NLA from MB. The OE part was $195 MSRP prior to NLA.

The only new one I'd use would be Hella, in a pinch. Facet, Delphi, and Meyle are all junk.

My preference would be a good used OEM sensor. However, if you are not getting any CMP faults, the cam sensor may not be an issue anymore.