Chrysler PT Cruiser cam sensor replacement: standard and turbo
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When the cam position sensor (or camshaft position sensor) starts to go, it is usually signalled by the Check Engine light, a code of P0340 being set, and the Limp In (or Limp Home) mode being activated. The engine will not go over 2,500 rpm and those with manual transmissions will hit the rev limiter. Clearing the code may temporarily help but eventually it will be set again.
The issue is sometimes a matter of wiring, so visually checking the wires as they go back to the computer from the camshaft position sensor is a good first step. However, the sensor itself is prone to failure after a mere 5-10 years, and only costs $35 at the local parts shop. Dealer parts may cost more.
Replacement is easy on a standard, non-turbocharged PT Cruiser and only a little harder on a turbocharged car. We did this repair on a PT Cruiser GT with the turbo 2.4 (full pressure). Do it when the engine is cold (that is, not when it has been running recently). As LisaLee pointed out, it's a good idea to disconnect the negative battery terminal first, as with all engine work.
First, get out your tools. You will need an 8 mm socket (with an extender if you have a turbo engine), a torque wrench measured in inch-pounds, and, for turbo owners, a straight 8 mm wrench. You also need a flat-bladed screwdriver, and, of course, a replacement sensor.
If you have a turbo 2.4, unscrew the turbocharger air feed (it’s the huge hose on top of the engine) and gently pull it off of the metal pipe on top. Remove the small air hose from the middle of the pipe and gently push it aside, just a few inches to your left (assuming you’re leaning over the grille). Don’t worry about removing the hole hose.
Open the air cleaner holder by undoing the two snaps, then loosening the air pipe fastener with the screwdriver (or a socket wrench) and gently pushing the hose off. Take out the filter, unplug the little hose on the left hand side (assuming you are leaning over the grille and radiator), and wiggle/pull the air cleaner box up.
The air cleaner box is not bolted in, but you should take note of how it’s positioned now, because you’ll need to push it back in later. It should pop out with a little muscle/wiggle.
Don’t be too concerned if there’s a little oil on the bottom of the air cleaner housing. That probably came from the crankcase ventilation system — which is also why you have that little hose that you had to pop out.
Once you’ve done this, you will see and be able to easily access the camshaft position sensor ... if you don’t have a turbo car. It’s right on the side of the engine near the top and is pretty unmistakeable as the only great big sensor attached to the engine.
If you do have a turbo engine — a GT or a PT Cruiser Limited with the light-pressure turbocharger — you will see that the sensor is nicely blocked by a serious-looking metal pipe attached to a rubber hose. You could take that off but I didn’t because it appears to carry oil or coolant and I don't want to mess with those unnecessarily. That’s why the turbo people need the straight wrench.
Now, use a small screwdriver to push the orange tab over to the side; you can slide the screwdriver underneath the tab and turn it to move it over. Then press the black tab and pull the wiring harness off. If your engine is warm, be careful about where the harness falls so it doesn't rest on anything hot.
The next step is to remove the sensor itself. For nonturbo people, just take out the two screws with the 8mm socket wrench. For turbo people, take out the one screw that you can reach that way (the far screw) with the 8mm wrench and extender, to avoid disturbing the hose. For the other screw, use the straight wrench and your patience.
The sensor will have some oil in it. This is normal, and the replacement sensor should come with a replacement seal in the box to keep the oil in. Clean the area around the sensor, being very careful not to get anything in the exposed area normally covered by the sensor. Then insert the gasket into the sensor and put it in. If, later, you get an oil leak, you can carefully use RTV to seal it — but, again, avoid getting any foreign material into that exposed bit of engine.
Put in the new sensor, checking the service manual for the correct torque. The tricky part here is that turbo owners must either get rid of that pesky hose or use the straight wrench to get the feel of the tightness of the screw they put in with the torque wrench, then tighten with the straight wrench. Either way, there’s not a lot of pressure involved — 115 inch-pounds (12 Nm). This is important, because the cam sensor apparently is also used as a cam tensioner.
Everything should go back together easily. Clear the codes either with battery disconnection or, preferably, a code reader — a chain store or dealer may be willing to do this for you. Check after a test drive to make sure the sensor is not leaking oil. If the problem re-occurs, there may be a wiring issue.
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