No Crank, No Start - Code A0B4 - Bmw 325i e90

[ace309]

Hello All,

I have a 2005 BMW 325i e90 6 speed manual with 110000kms. Car ran fine one night and then in the morning it didn't start. Here are the symptoms and what i've tried so far.

keyfobs locks/unlocks doors... put in key, dash lights up, radio, heater fans work fine... I can hear the fuel pump prime. press the engine start button, no clicking sound, no dimming of the lights, no crank, no start...

Spent a few days doing the following...
1) Tried Jump Starting the car with my friends car... no crank, no start.
2) Tried both key fobs... no crank, no start.
3) Installed NEW battery - Voltage 12.4V at battery (registered it with carly app) (In carly app, it shows 11.78V for some reason)
4) Installed NEW Bosch Starter - has 12.3V to the starter solenoid wire
5) Checked battery terminals, all seem good. I noticed there was IBS cable or it was replaced with a generic ground wire. No voltage drop across it to the frame. I've driven like this for an entire year before realizing now that it doesn't have an IBS cable... so car should be fine.
6) Used jumper cables from the negative post in the engine bay to engine (to add another engine ground), tried to start but still no crank. When testing from + post in engine bay to the engine itself, I get 12.2V. So engine is grounded correctly. + wires seem to sending correct voltage to starter.

Pulled the following code... CAS: Error engine start starter operation A0B4 Code: 00A0B4 (not sure how to diagnose this) Cleared codes... no crank, no start.

I am digging around for wiring diagrams to check 1) which fuses to test, 2) how to test the white wire on the starter (don't know how to test this yet with a simple multimeter or what values I should be getting...) as well as 3) test the CAS pins 21/22 (don't know how to do this either yet).

If anyone can lay out how to do any of the above with a DIY (with photos/video) or what else I can check for, I would greatly appreciate it.

[bmwdirtracer]

Hi Ace, and welcome to the forum.

I have to start with the fact that your battery is not charged. A good battery should show 12.6 volts. The fact that carly says it's 11.78 tells me maybe your multimeter is reading incorrectly? Worth checking, anyway.

Good job, on connecting the jumper cable from frame to engine. Testing with a multimeter for this is useless, because there's no load involved, and that's when a bad ground fails.

To test the activation wire at the starter, the easiest way I've found, on your engine, is to use a long pair of needlenose pliers and a long screwdriver to unplug the connector, reaching down between the intake manifold runners. (This is not easy, but it is possible). Then using the needlenose pliers, pull that plug up high enough to put a test light in it....and have someone press the start button, foot on the clutch of course.

Here are all your wiring diagrams:
https://www.newtis.info/tisv2/a/en/

[ace309]

Multimeter shows 12.4V at battery, not sure why the Carly app shows 11.78V. As said above, even jumping the car on a good battery (from a running car), no crank, no start. So I don't think voltage is an issue.

What am I checking on the activation wire anyway? When you press the start button, does it send 12 volts to it? If it does (what does that mean) and if it doesn't (what does that mean)

that the starter is bad? But its new!

What about the A0B4 code?

[bmwdirtracer]

You will be looking for 12+ volts at the activation terminal. If there IS 12+ volts when the starter button is pushed, and all main hots and grounds are good, your new starter is bad.

A0B4? I don't know, sorry. All my scan tools speak English. ISTA or Autologic would tell me what factor actually causes that code.

Maybe 328 Power 04 will see this thread; he might have a culprit to go with the code number.

But again, if you get 12+ volts at the activation terminal, the problem is the starter, new or not.

I have received many brand new parts that were bad, straight out of the box.

[White94RX]

Recently another tech had a similar issue. Turns out the power wire going to the starter had rusted or corroded itself inside the insulation somewhere within the 6" of cable from the connection just below the jumper post, and the plastic housing where it goes across and above the engine. I think it was actually right off the wire terminal. It's worth checking. He had B+ at the starter terminal, but there was no way any amperage could feed the starter through the broken/corroded cable.

[Breeze1]

Hello All,

I have a 2005 BMW 325i e90 6 speed manual with 110000kms. Car ran fine one night and then in the morning it didn't start. Here are the symptoms and what i've tried so far.

keyfobs locks/unlocks doors... put in key, dash lights up, radio, heater fans work fine... I can hear the fuel pump prime. press the engine start button, no clicking sound, no dimming of the lights, no crank, no start...

Spent a few days doing the following...
1) Tried Jump Starting the car with my friends car... no crank, no start.
2) Tried both key fobs... no crank, no start.
3) Installed NEW battery - Voltage 12.4V at battery (registered it with carly app) (In carly app, it shows 11.78V for some reason)
4) Installed NEW Bosch Starter - has 12.3V to the starter solenoid wire
5) Checked battery terminals, all seem good. I noticed there was IBS cable or it was replaced with a generic ground wire. No voltage drop across it to the frame. I've driven like this for an entire year before realizing now that it doesn't have an IBS cable... so car should be fine.
6) Used jumper cables from the negative post in the engine bay to engine (to add another engine ground), tried to start but still no crank. When testing from + post in engine bay to the engine itself, I get 12.2V. So engine is grounded correctly. + wires seem to sending correct voltage to starter.

Pulled the following code... CAS: Error engine start starter operation A0B4 Code: 00A0B4 (not sure how to diagnose this) Cleared codes... no crank, no start.

I am digging around for wiring diagrams to check 1) which fuses to test, 2) how to test the white wire on the starter (don't know how to test this yet with a simple multimeter or what values I should be getting...) as well as 3) test the CAS pins 21/22 (don't know how to do this either yet).

If anyone can lay out how to do any of the above with a DIY (with photos/video) or what else I can check for, I would greatly appreciate it.

Did you pull that code before or after replacing the starter? According to a quick internet research it could be due to different issues, all related to ignition; a few possible culprits listed here.

And according to this your car could start if you waited a minute or so before pushing the button (might not work but it costs nothing to try it)

I would check the fuses if I were you.

[MarcoZandrini]

Can the voltage at the starter’s main power connection be checked when the start engine button is pushed? That way OP can see the voltage drop across the starter. Just a thought.

[MIKYZZ4]

Perform this quick test:
Have someone knock a wrench or small hammer against the starter solenoid,
while you simultaneously try to crank the engine over. Post back result.

[328 Power 04]

That code is just CAS module telling you that it tried to start the car and starter failed at cranking.

Checking the voltage, the starter and solenoid, and wiring is a good idea.

[bmwdirtracer]

Thanks Abel, and White 94 Rx.

[ace309]

Just wanted to update this thread in case anyone else has this issue. The NEW starter was fine, battery was fine, all connections to the starter was fine except for the trigger wire that is connected to front of the starter. It is a small white wire with a quick connecter clip on it. When you press the start engine button, it sends 12 volts to the starter to crank the engine. Even though it looked like it was connected, it was not and i literally pulled it off by hand. I had to press it onto the starter quite hard and wiggle it around a bit until you hear it audibly click, so when you pull on it, it no longer comes off.

Thanks for all the help troubleshooting, great community!

[OjaiE60]

So the issue was your starter?
Once you replaced it with the new one AND securely connected the wire all was good?

I'm having similar issue. The car all of a sudden randomly starts and I receive the A0B4 code when it doesn't.

New starter on order from FCP Euro.

I've replaced the relay, tried disconnecting IBS, checked grounds, etc. I did tap starter a few times after it wouldn't start-- it started up, then didn't start again. Weather has been on the warm-side, and I've read heat seems to contribute to the issue.

Replacing is a pain, so I'm just hoping not to go through all the work just to have it continue with the new starter.

Note, mine is an n52 E60.

Thanks

- - - Updated - - -

... also, confirmed battery is 100% good.

[abranch66]

Hello, so I’m popping same error code as noted with same no crank, no start situation. This is on 2008 BMW 535i w/ n54 engine. I’ve done a lot of diff diagnostics up until we energized the starter and you can hear the starter spin but it doesn’t engage. Does anybody have any knowledge or advice on this issue? Thanks in advance and I look forward to any help.

[bmwdirtracer]

Starter spins but doesn't engage = starter bendix faulty. Replace starter with a new or Bosch FACTORY remanufactured unit. Do NOT get a cheap rebuild at a local parts store!

[nova23zz502]

No Crank No start little life in instrument cluster. Radio and vehicle info staulk is working. Can not shift out of park. 2007 e60 n52 530 Xi. Currently has 121000 thousand miles, completely stock OEM, no comfort access feature. 2^nd owner since 18K miles. No accidents. An attempt to jump the car from terminals under hood without success. A new battery was purchased and installed, still no crank nor start. Ground was checked at multiple levels. My volt-meter reported 12.2 volts at battery terminal, B+ terminal, engine, grounds.


Current Status Quo: Still No crank, no start. At this time the Car unlocks and locks with remote/key. All functions of remote work. The Moment car is unlocked or door opened, the instrument cluster will assume control and illuminate. There is P (park) illumination however the gear selector button does not work when pressed. I have noticed the LED light on the gear shift selector and the ignition start/stop button will be illuminate.

[bmwdirtracer]

Well, 12.2 volts is a battery at ~15%; it should be 12.6, at the very least.

Secondly, you really need to read codes from all computers with a BMW specific scan tool.

Third, my crystal ball says you need a new (not local Autozoo rebuild) starter/ (Crystal ball does not equal good BMW scan tool or testing !!!)