How to fix a bad Angle Sensor
Sorry for the pic layout, but i couldn't figure out how to add a pic after each step. so the numbers after each step go to the pics in order from left to right.
This is some very helpful info I learned about angle sensors and the fact that probably a big majority of them can possibly be fixed instead of the need to be replaced. All they consist of is a pair of contact brushes mounted to a small spring loaded wheel that turn along an electrically conductive strip that varies in resistance from one to the other. Unless serious damage has occurred to the brushes or the strip(physical damage, excessive wear to the brush tips or resistance strip), there's really not much that can mechanically go wrong with them. Over time, the o-ring that seals the sensor to the engine case can dry out and shrink allowing water to enter the sensor housing through a couple small holes in the backplate and around the sensor shaft. This can lead to a build up of oxidation on the contacts which in turn create more resistance or can completely disrupt the connection between the contact points, both of which will give false readings which produce error codes and ultimately lead to the sensor being trashed and replaced.
All you need is a few simple tools and a DMM (digital multimeter). An analog volt/ohm meter can be used but isn't as accurate as a digital meter so it's possible to false readings with an analog meter.
Tools: X-acto or similar razor blade
Needle nose pliers or tweezers
Ultra fine needle files or some very fine grit sand paper
Electronic contact cleaner (not necessary, but recommended)
Silicone (I use Permatex Ultra Black)
First off, test to confirm the sensor is out of spec. Download a service manual for your model which will have the specifications for the sensor and the steps for testing. Once it is determined that the sensor is faulty, it's time to grab your razor and cut it open. First, use the razor to make a couple marks on the sensor housing and backplate so you'll know where to position the plate during reassembly. This is necessary cause the spring inside is slightly torqued which allows the brush wheel to return to it's at rest state. To do this, look on the engine side of the sensor and you'll see a small thin ring around the outside of the backplate. Take your razor and slide under this lip and cut all the way around, breaking the lip off as you go.
Next, carefully pull the backplate off, if it hasn't already popped out (there is a spring underneath so be ready). Now, use extra care and remove the brush attachment. Be very careful not to damage the tips of the contact brushes which are very finely stranded metal and can bend or break off if not careful.
Next, using needle nose pliers or a set of tweezers, remove the resistance strip retaining clip then carefully remove the resistance strip itself. The strip will have 3 small contact points at one end, which in most cases, get oxidized and corroded due to moisture. Also, the contact pins which remain in the sensor housing will also get oxidized and corroded.
Once completely disassembled, carefully clean the contacts on the sensor housing using needle file or sandpaper. If you have some electronics cleaner, spray them off once done. Now, you must be EXTRA CAREFUL when cleaning the contact points on the resistance strip. These contacts are very very VERY thin strips of metal and can be easily damaged. My advise is not to use sandpaper on these. I used the tip of a needle file and very gently scraped till the contact was shiny then washed with contact cleaner.
Once everything is cleaned, apply a small dab of dielectric grease to the center of the sensor housing where the brush attachment sits. This will make the brush wheel turn easier and also help repel moisture. Insert the brush wheel paying attention not to damage the brush tips. Reinstall the spring as it came out (each end of the spring has a different bend and will only go in one way which will be obvious) and place the backplate onto the spring, and squeeze back together into the housing realigning the backplate with the marks you made in the beginning. I used a couple small clamps the hold it together as I applied a couple drops of super glue. Once the glue is dry, remove the clamps and apply glue all the way around and allow to completely dry. Once dry, use your meter to verify that all your work has paid off by testing again using the procedures in the service manual.
Reinstall sensor into the sensor bracket. I applied a little bit of Permatex Ultra Black silicone on top of the o-ring to ensure a good water tight seal to the engine case. Reinstall the sensor to the case, being sure to preload before installing the bolts, and torque to specs. Apply a dab of dielectric grease to the plug and reattach the harness. If done correctly and considering that the sensor was salvageable, you just saved yourself $50-$100 bucks. I hope this helps someone in the future. I know it fixed my problem and saved me money that I can use on something more desirable.
Last edited by joeyglvr; 10-09-2012 at 12:38 AM.