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Hi My son has an Alfa 156 TI, 2004 2ltr selespeed and it wont start I don't have a spark but I have fuel from.From what I know and read online the crank sensor may be the problem, how do I check it and also where is it and what's the best way to get to it? Cheers Martin
 

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The best way to check it is diagnostically. A reading of live data would do it (select only crankshaft sensor). Then turning the engine on the starter motor should reveal a reading of 300rpm.

Alternatively, remove engine top cover and unbolt a stick coil. Ideally fit a surplus spark plug into the stick coil and earth it onto the cam/valve cover. Cranking engine should reveal the plug to spark (taking care about high voltage). I have assumed it is a JTS here. If it is a Twinspark, the same largely applies but only remove an HT lead and be sure to earth it properly as Twinspark cam covers are plastic. The TI is the trim and AFAIK, Selespeed versions could be TS or JTS.

The crank sensor is located near the flywheel at the rear of the engine below the throttle body. It is retained with a bolt with a 10mm external hex (10mm spanner). I find best access is to remove induction pipes (secured with Clic-R clips which need Clic-R pliers to refit or new large jubilee clips). I also remove the throttle body itself (4 Torx bolts) to be able to get me arm down to reach the crank sensor. The crank sensor has an o ring oil seal. Ensure it comes out with the sensor, otherwise remove it carefully with a small flat screwdriver.
 

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No it’s just below. Here a link how to from alfaworkshop. You really could do with diag software. Just renewed mine. There is an app called multiecuscan. Does all alfa, fiat etc. It’s £50 but worth it’s weight gold but the unpaid version will at least tell you the error code. You just won’t be able to clear codes.

https://www.alfaworkshop.co.uk/alfa_147_156_gt_crank_shaft_sensor_replacement.shtml

You’ll need an OBDII reader. Bought this one for next to nothing off eBay and works fine with app.

WiFi OBD2 ELM327 Bluetooth Car Scanner Android iOS IPhone Torque Auto Scan Tool https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.co.uk/ulk/itm/401620435469
 

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If your car case the crank sensor with its connector up on top of the inlet, it is a brown connector.
A simple test is to measure the resistance. If it has got up close to 1kOhm, it won't work.
When they start to fail, they fail when hot (you can measure and see the high resistance), then as they cool you see the resistance drop, when it has dropped enough the car will start.

Later crank sensors didn't have a long cable attached, so that check isn't so easy.
 
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