Never Ending Cam Sensor Issue

wessock · Post by **wessock** » Wed Mar 04, 2009 12:35 am

2000 Lanos 1.6L

Background: For about a year now I've had an intermittent CEL code PO342 about the camshaft position sensor. Took it to a dealer when it started to get the sensor replaced under the recall and they say they replaced it. Problem never went away but it wasn't affecting anything so I let it go until last month when I had to get the car inspected. The problem never got worse and there seemed no rhyme or reason to when it came on. Never get any other codes showing up. I replaced the wiring from the ECU to the sensor, ground, and power. Didn't solve anything. Replaced the EGR valve, fuel filter, plugs, throttle position sensor, intake air temp sensor, idle air controller, cleaned the throttle body, checked vacuum lines, and nothing changed.

Today I noticed something though. The code seems to kick when the thermostat opens up. When the temp needle ticks down a little when the cooler coolant is released, that seems to be when the code pops up. It's not every time, but enough for me to pay attention to it the last few days to notice it. This can be at idle or on a highway. So what exactly is happening in the engine when the t-stat opens up that could be making the camshaft sensor code trigger? Any ideas?

buddha102 · Post by **buddha102** » Wed Mar 04, 2009 1:01 am

got the same problem, it shows up about 90% of time, doesint effect nothing when im driving

wessock · Post by **wessock** » Wed Mar 04, 2009 1:10 am

I have noticed lately my fuel consumption is a little higher. Instead of like 32 mpg average, I'm getting 26-29. I assume it's because the engine is going into the special mode that doesn't use the cam sensor for timing. Oh, also forgot to mention before . . . When I start the car with no CEL or codes, and then the CEL lights up with the code during driving, it will often turn itself off at the next start up or 2. According to the manual and other sources, it's supposed to stay on for 4 on/off cycles of normal operation. I think that's a little odd that it's resetting faster than it's supposed to.

Daniel · Post by **Daniel** » Wed Mar 04, 2009 8:41 am

So what exactly is happening in the engine when the t-stat opens up that could be making the camshaft sensor code trigger?

Here my interpretation. When t-stat opens it offers a second path to the water pump to flow coolant. Less work (torque)for the pump and maybe a slight variation in t-belt tension and relative position of camshaft.

Did I already gived you this link about t-belt thickness? It's maybe a path to investigate. http://autos.groups.yahoo.com/group/dae ... sage/11570 .

Daniel

MMamdouh · Post by **MMamdouh** » Wed Mar 04, 2009 2:23 pm

on the same yahoo group, Chris used the aveo cam position sensor as a replacement to the daewoo one

MMamdouh

wessock · Post by **wessock** » Wed Mar 04, 2009 2:40 pm

That link was interesting. I've been in there checking timing marks, the belt, and the sensor a number of times recently and didn't notice anything abnormal about the belt. Definitely no grooves on the back. I'll have to double check, but I'm pretty sure I had a Gates belt put on there with the kit last belt change. The camshaft problem popped up about a year after the change too so I'd think it would affect it sooner if that was the problem. I'll definitely keep it in mind though.

wessock · Post by **wessock** » Wed Mar 04, 2009 3:05 pm

Yeah I tried to put an aveo sensor in and it wasn't reading it or the connector clip wasn't plugging in far enough. Lol, I thought it was in there fine but it was throwing the code right away each ECU reset. I was doing quite an angry dance. I've swapped cam sensors so many times I can do it in my sleep now. I have a third sensor coming to me just to make sure that the 2 I have aren't the problem. I'm still not convinced my dealer actually replaced it under the recall.

wessock · Post by **wessock** » Wed Mar 04, 2009 3:23 pm

What about the coolant sensor or the O2 sensor? Any view points on them being possible causes? Those are my next items down the list if I have to.

Daniel · Post by **Daniel** » Wed Mar 04, 2009 5:13 pm

wessock wrote:What about the coolant sensor or the O2 sensor? Any view points on them being possible causes? Those are my next items down the list if I have to.

They will give you other codes.

I'm pretty sure you have a bad contact somewhere and no faultly cam sensor. Have a look at ECM connectors too (gently pull wires). I know tracing this kind of intermittent problem can be a nightmare.
Do you already have some drawings to follow the wires?

From service manual:
"Faulty Electrical Connections or Wiring

Most intermittent problems are caused by faulty electrical
connections or wiring. Perform a careful inspection of suspect
circuits for the following:
Poor mating of the connector halves.
Terminals not fully seated in the connector body.
Improperly formed or damaged terminals. All connector
terminals in a problem circuit should be carefully
inspected, reformed, or replaced to insure contact
tension.
Poor terminal–to–wire connection. This requires
removing the terminal from the connector body."

Daniel

wessock · Post by **wessock** » Wed Mar 04, 2009 5:34 pm

Yeah I already did all of that. The ECU connectors look fine. I rewired the signal wire from the ECU and the ground to bypass all middle connectors, even replaced the cam sensor's connector, same problem. I haven't rewired the power since it shares with the injectors and they seem to be running fine. I know the O2 and coolant sensors aren't dead, but maybe they are not sending accurate signals. My current theory is that some other sensor is malfunctioning enough to cause an error with the cam sensor, but not enough or in a certain way to cause it's own error code. The cam sensor seems to be very sensitive as far as throwing codes. Since the code seems to get triggered when the thermostat opens, that's why I figured I'd change the coolant sensor.

Puddle31 · Post by **Puddle31** » Wed Mar 04, 2009 9:06 pm

wessock, I think I put this in before but mine did (does) the same thing. I have found that if I keep the airflow from the heater off the floor, the code will clear and will not come back. If my air flow switch accidently slides down and the heat flows through it, I will get the code again. don't ask me why, I have no idea, but I can clear it and keep it off for inspection..... at least for now!

wessock · Post by **wessock** » Wed Mar 04, 2009 9:29 pm

Yeah I kept your problem in mind but keeping the heater off of the floor didn't make a difference with me. I did pas my inspection last month though because it stayed off long enough for it. Little bastard came on on the way home from the inspection though. I really didn't want to pay my mechanic to figure it out. I admit though that it's becoming a far bigger problem than I thought it ever would be.

wessock · Post by **wessock** » Wed Mar 04, 2009 10:04 pm

Have you tried anymore to figure out what the actual problem is Puddle?

wessock · Post by **wessock** » Thu Mar 05, 2009 3:52 pm

Anybody else have any ideas or input on what exactly happens in the engine or sensors when the thermostat opens up releasing a surge of cooler coolant that could affect the camshaft sensor?

Daniel · Post by **Daniel** » Thu Mar 05, 2009 8:10 pm

wessock wrote:Anybody else have any ideas or input on what exactly happens in the engine or sensors when the thermostat opens up releasing a surge of cooler coolant that could affect the camshaft sensor?

No, sorry

.
What is expected is a slight drop in coolant temperature (sensor). But you already know that.
Try to monitor the line signal from camshaft sensor itself. That can take the form of a LED, missing pulse detector, SCANTOOL, audio,...

So you can sort the problem when it happens:
CEL together with "monitored" detection:--->problem in front of pick-up signal.
CEL without "monitored" detection:--->problem aft pick-up signal. (ECU? Bad solder joint inside ECU,...?)

Puddle,
Your ECU is under co-driver seat, right? Heat on the floor could affect it.
Could it be a bad solder joint inside ECU for you too?

That's my 2ct