Engine Cranking But Not Starting - A0B3 Terminal 50 Code

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Wilko102 W So after replacing a valve cover and spark plugs i accidentally didnt put the ground wire back on the front nut infront of the valve cover. Started the engine few sparks and i turned it off quickly! Now it won't start! Arghh! Error code coming up on my scanner A0B3 - Terminal 50 Starter Motor. It has been sat on my drive so battey low but have obviouly tried it jump starting. I have also tried: 1)Checking all fuses in engine compartment box. 2) Checking the fuse box by the battery and it is fine. 3? Swapping over the K6300 Relay with another similar relay that controls the radiator just to see if it was a faulty relay. Nope still not starting. 4)Checked spark plugs (not wet and look fine) 5) Checked camshaft sensor is in fine etc 6) Check 12v is going to the fuse box from the battery. 7)Checked all grounds are solidly secured. I'm going mad dont know what else to try. Does anyone have any ideas?! I'll buy them 10 pints if they help me!!!! I'm going crazy! It cranks fine like i said! #1 · Mar 18, 2019 So after replacing a valve cover and spark plugs i accidentally didnt put the ground wire back on the front nut infront of the valve cover. Started the engine few sparks and i turned it off quickly! Now it won't start! Arghh! Error code coming up on my scanner A0B3 - Terminal 50 Starter Motor. It has been sat on my drive so battey low but have obviouly tried it jump starting. I have also tried: 1)Checking all fuses in engine compartment box. 2) Checking the fuse box by the battery and it is fine. 3? Swapping over the K6300 Relay with another similar relay that controls the radiator just to see if it was a faulty relay. Nope still not starting. 4)Checked spark plugs (not wet and look fine) 5) Checked camshaft sensor is in fine etc 6) Check 12v is going to the fuse box from the battery. 7)Checked all grounds are solidly secured. I'm going mad dont know what else to try. Does anyone have any ideas?! I'll buy them 10 pints if they help me!!!! I'm going crazy! It cranks fine like i said! See less See more Sort by Oldest first Oldest first Newest first Most reactions #2 · Mar 18, 2019 have removed the earth strap on the front engine mount to chassis. also battery needs to be charged before trying to crank them believe me its not worth the risk cranking a engine with flat battery and jump leads with a running jump start vehicle attached.. chances of spiking the ECU is fairly high seen many over the years in all kinds of ecu controlled cars from spiking the system, AA RAC have guide lines to turn on the head lights of cars they are jump starting to help direct any surges that can spike a ecu.. apart from checking the earth straps and all the fuse's one after another with multimeter just in case one is cracked and cant see it,, believe me such a bugger after not starting with this process to find a day later it was cracked fuse, multi meter on ohms resistance bleeper check them all. after all that need a diagnostics tool best for the money is autocom cdp plus, £30 on ebay dont let price put you off its the best for money beats £300 scanners to be honest, the CAS units on these bmw products are rubbish you could try locking the car for 10 minutes let it sleep ie ecu will shut down then open with key fob try again see if will start #3 · Mar 18, 2019 below link company who repair them CAS unit https://www.sinspeed.co.uk/cas3-immobiliser-repair/ #4 · Oct 30, 2020

Wilko102 said: So after replacing a valve cover and spark plugs i accidentally didnt put the ground wire back on the front nut infront of the valve cover. Started the engine few sparks and i turned it off quickly! Now it won't start! Arghh! Error code coming up on my scanner A0B3 - Terminal 50 Starter Motor. It has been sat on my drive so battey low but have obviouly tried it jump starting. I have also tried: 1)Checking all fuses in engine compartment box. 2) Checking the fuse box by the battery and it is fine. 3? Swapping over the K6300 Relay with another similar relay that controls the radiator just to see if it was a faulty relay. Nope still not starting. 4)Checked spark plugs (not wet and look fine) 5) Checked camshaft sensor is in fine etc 6) Check 12v is going to the fuse box from the battery. 7)Checked all grounds are solidly secured. I'm going mad dont know what else to try. Does anyone have any ideas?! I'll buy them 10 pints if they help me!!!! I'm going crazy! It cranks fine like i said! Click to expand...

Hi buddy I have the same problem, did you fix it ?? Going crazy !!! #5 · Nov 22, 2020 Hi all just some backyard advice ..I had a 'crank no start" condition also...cost me 600 CAD to tow and the "experts " dd not find problem....enter youtube...there is a 15 or sometimes 20 amp fuse under hood...no pic's but its closest to the firewall and closest to driver fender...hope that does it #6 · Mar 6, 2021

Wilko102 said: So after replacing a valve cover and spark plugs i accidentally didnt put the ground wire back on the front nut infront of the valve cover. Started the engine few sparks and i turned it off quickly! Now it won't start! Arghh! Error code coming up on my scanner A0B3 - Terminal 50 Starter Motor. It has been sat on my drive so battey low but have obviouly tried it jump starting. I have also tried: 1)Checking all fuses in engine compartment box. 2) Checking the fuse box by the battery and it is fine. 3? Swapping over the K6300 Relay with another similar relay that controls the radiator just to see if it was a faulty relay. Nope still not starting. 4)Checked spark plugs (not wet and look fine) 5) Checked camshaft sensor is in fine etc 6) Check 12v is going to the fuse box from the battery. 7)Checked all grounds are solidly secured. I'm going mad dont know what else to try. Does anyone have any ideas?! I'll buy them 10 pints if they help me!!!! I'm going crazy! It cranks fine like i said! Click to expand...

Wilko102 said: So after replacing a valve cover and spark plugs i accidentally didnt put the ground wire back on the front nut infront of the valve cover. Started the engine few sparks and i turned it off quickly! Now it won't start! Arghh! Error code coming up on my scanner A0B3 - Terminal 50 Starter Motor. It has been sat on my drive so battey low but have obviouly tried it jump starting. I have also tried: 1)Checking all fuses in engine compartment box. 2) Checking the fuse box by the battery and it is fine. 3? Swapping over the K6300 Relay with another similar relay that controls the radiator just to see if it was a faulty relay. Nope still not starting. 4)Checked spark plugs (not wet and look fine) 5) Checked camshaft sensor is in fine etc 6) Check 12v is going to the fuse box from the battery. 7)Checked all grounds are solidly secured. I'm going mad dont know what else to try. Does anyone have any ideas?! I'll buy them 10 pints if they help me!!!! I'm going crazy! It cranks fine like i said! Click to expand...

Hi is Simon from South Africa I had the same problem u r having, this is how I fixed it, I did all checks like u, fuses, relay and so on. Only today I thought why can't I buy a crank sensor even though my old one looks fine but didn't give me Rpm when starting the car. I then bought a new sensor, unplugged the ground battery cable and replace a crank sensor by a new one , UPPS the car started n I am so happy the stress is gone, so try it . I'm even planning to buy new sensors for the whole vehicle. Thanks #7 · Mar 6, 2021

Wilko102 said: So after replacing a valve cover and spark plugs i accidentally didnt put the ground wire back on the front nut infront of the valve cover. Started the engine few sparks and i turned it off quickly! Now it won't start! Arghh! Error code coming up on my scanner A0B3 - Terminal 50 Starter Motor. It has been sat on my drive so battey low but have obviouly tried it jump starting. I have also tried: 1)Checking all fuses in engine compartment box. 2) Checking the fuse box by the battery and it is fine. 3? Swapping over the K6300 Relay with another similar relay that controls the radiator just to see if it was a faulty relay. Nope still not starting. 4)Checked spark plugs (not wet and look fine) 5) Checked camshaft sensor is in fine etc 6) Check 12v is going to the fuse box from the battery. 7)Checked all grounds are solidly secured. I'm going mad dont know what else to try. Does anyone have any ideas?! I'll buy them 10 pints if they help me!!!! I'm going crazy! It cranks fine like i said! Click to expand...

Wilko102 said: So after replacing a valve cover and spark plugs i accidentally didnt put the ground wire back on the front nut infront of the valve cover. Started the engine few sparks and i turned it off quickly! Now it won't start! Arghh! Error code coming up on my scanner A0B3 - Terminal 50 Starter Motor. It has been sat on my drive so battey low but have obviouly tried it jump starting. I have also tried: 1)Checking all fuses in engine compartment box. 2) Checking the fuse box by the battery and it is fine. 3? Swapping over the K6300 Relay with another similar relay that controls the radiator just to see if it was a faulty relay. Nope still not starting. 4)Checked spark plugs (not wet and look fine) 5) Checked camshaft sensor is in fine etc 6) Check 12v is going to the fuse box from the battery. 7)Checked all grounds are solidly secured. I'm going mad dont know what else to try. Does anyone have any ideas?! I'll buy them 10 pints if they help me!!!! I'm going crazy! It cranks fine like i said! Click to expand...

#8 · Jun 3, 2022

Wilko102 said: So after replacing a valve cover and spark plugs i accidentally didnt put the ground wire back on the front nut infront of the valve cover. Started the engine few sparks and i turned it off quickly! Now it won't start! Arghh! Error code coming up on my scanner A0B3 - Terminal 50 Starter Motor. It has been sat on my drive so battey low but have obviouly tried it jump starting. I have also tried: 1)Checking all fuses in engine compartment box. 2) Checking the fuse box by the battery and it is fine. 3? Swapping over the K6300 Relay with another similar relay that controls the radiator just to see if it was a faulty relay. Nope still not starting. 4)Checked spark plugs (not wet and look fine) 5) Checked camshaft sensor is in fine etc 6) Check 12v is going to the fuse box from the battery. 7)Checked all grounds are solidly secured. I'm going mad dont know what else to try. Does anyone have any ideas?! I'll buy them 10 pints if they help me!!!! I'm going crazy! It cranks fine like i said! Click to expand...

Hi there mate. Your ECU got compromised by you not connecting the ground wire and got burnt Insert Quotes Post Reply

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