My Disco recently wouldn't start after driving to town. I took it to a shop to diagnose.

They told me it was the crank sensor, or the plug to it as they were both wet from my head gasket that's leaking slowly. Ouch!. Questions for my next post.

The next day, it started up and ran, glitched a couple times over 40 mile trip, (similar feeling as when u run a car with a really bad plugged fuel filter). But it was very brief. So the plug or sensor are still wet inside?

This sensor is really hard to get to as some know, and i'm not the smallest guy. So I would like to leave this sensor alone if i can. If it is working now, does that mean it never went out, and was more likely the connection was wet?

Or can these sensors work one day and not the next? And i should just replace it?

2002, Disco 2, 130k miles, stock, complete tune up, water pump, daily driver

 

My experience was that it got progressively worse. It failed after the car wash, let it sit for an hour with the hood up, drove it home (30 mins away)

Next, driving to work 2 days later thinking I had no issue - I hit some deeper snow as I crossed over state lines and boom, out she went. Towed home.

It would not start at all once I got it home.

I fiddled with ground points thinking that it still may not be that sensor, and just weird coincidence. Got it to start again. Backed it out, poof, out again in the driveway. Let it sit for an hour, got it to start and drive forward enough to get the front axle in before it died. Gave it one more crank there and luckily got the rear axle in the garage too.

Replaced sensor, ZERO issues again until the car wash on Friday, maybe 1000 miles later.

RockAuto Parts Catalog - crankshaft position sensor - AIRTEX Part # 5S1880 Sensor I was sent is Bosch, made in Germany.

 

Go to Lucky 8 and read their directions on replacing the sensor before it leaves you stranded, it is not going to get any better.

 

Here is a pix of a sensor innards, a coil of wire around a pin. The pin is aligned to the drilled reluctor disk, that thing with slots in the oil pan pix. On the D1 they use a series of stamped tabs on a metal disk, which can get bent or sheared off. With very exact spacing, the drilled spots in the disk flying by just fractions of an inch away cause a very weak electrical signal to be genereated. The signal is in-step with the drilled spots, and provide the index of where the crankshaft is. The ECU then issues spark and timing based on that.

If you had a bad connector or cracked wiring harness (it is a shielded cable) you could have water bothering it even with a brand new sensor. If sensor has developed a "cold" solder joint or corrosion it can have a mind of its own. Generally once they go bad, they continue to cause problems at increasing frequency.

If you DIY install will need to plug in and let it hang before mounting block/sensor/spacers/nuts. Get the spacing wrong and it won't crank. Some say they used a long pair of needle nose pliers to get at connector. These are parts that come off along with the sensor.

Attached please find pages form the Bosch ECU manual which tells more. If an indy shop has done several of them in the past they may only charge 1 hour labor.