Pilot striking but burner does not light does not show a code

Clean thermopile check volts on it should 600 mile volts .

Tankless?... call service technician

Tank? clean arrestor screen, replace gas valve thermostat
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html

http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent

Gene

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

I believe this is a hydro-sparker pilot ignition then burner on when T-Couple/Flame Sensor acknowledges pilot lit.
W/O the signal feedback the Gas Valve will not open and light burner.
This is a Technician Service Job as you have insufficient knowledge to DIY this potentially dangerous LP/NG Control Valve/Sparker Assembly
I assume that lack of knowledge by your lack of a Manual for the Unit
You cannot force ignition on a hydro-sparker manually.

Natural Gas: Pilot burner or orfice may need to be cleaned. Pg 11 manual.
http://www.boschhotwater.com/Portals/7/TechManuals/125BL_English.pdf
Most tank and tankless gas water heaters today suggest annual cleaning and maintenance of burner.

Open following links for Bosch troubleshooting resources:
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html
http://www.boschhotwater.com/HelpfulResources/TechnicalSupport/BoschAquaStarModels/125BLTechSupport/Troubleshoot/tabid/474/Default.aspx

Open following link for Bosch tankless troubleshooting resources, including Bosch contact information, typical manuals, error codes, tech support, parts, fuel-saver calculator, service bulletins, water heater forum, fixya links, disclaimers, and links for finding service technician.
http://waterheatertimer.org/Troubleshoot-Bosch-Tankless-water-heater.html

Before calling service technician, read manual for fault finding and possible solutions.
Read manual cover to cover, make sure tankless receives yearly maintenance as outline in manual.
http://waterheatertimer.org/pdf/Bosch_water-wizard.pdf
http://waterheatertimer.org/pdf/Bosch_13P_16P_In.pdf

Following links talk about keeping pilot lit, and describe location somewhat. Bosch water wizard has standing pilot light.
http://www.fixya.com/support/t2961646-water_wizard_10p_pilot_light_keeps_going
http://www.fixya.com/support/t2960079-bosh_water_wizard_10p_pilot_light_keeps
http://www.fixya.com/support/t6182021-bosch_10p_tankless_hot_water

1) The manual does not show diagrams you asked for.

2) Website that sells Bosch parts does not show parts for water wizard, nor does Bosch site for parts: Instruction manual says: replace pilot injector
http://www.boschhotwater.com/HelpfulResources/PurchaseParts/tabid/837/Default.aspx
http://www.houseneeds.com/shop/heatingproducts/waterheating/parts/bosch2400espartsbuy.asp#

3) Searching "pilot injector for Bosch Water wizard" turns up fixya questions which is generally bad news for do-it-yourselfer because it means information sources are through service technician.

4) As a general rule, tankless are not do-it-yourself repairs or installation because they are affected by so many internal and external factors, including air quality, air flow, venting, other gas appliances, gas pressure, gas supply, water pressure, water flow, plumbing problems, water quality, plus internal parts and including any combination of things listed above..
Replacement parts each come will disclaimer.

Add a comment with your experience so others with same-similar problem can benefit.
Send some photos so the internet can see the problem.
http://www.fixya.com/support/r6568559-post_photograph_fixya_questions_answers

Also take advantage of fixya expert assistance live.
For a price, expert works with you while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

the sparkers do go bad and usually can be replaced. you should be able to light the pilot by hand with a long lighter that is used to light a grill.

The sensor that allows the pilot to ignite is at fault
replace the probe that points at the pilot light which is the sensor

ok make sure u turn everthing thing off then wait 5 min then turn the dail that controls the heat on it to pilot light then turn the gas nob to pilot then ignit it once lit wait a few seconds and turn gas nob to on pisition then turn heat dail to were the arrow is not to a b or c cause the gas is to high it will blow it self out

Thermo coupler may be defective. it controls the main gas valve by closing main if pilot is out. make sure thermo coupler bulb is positioned over and near tip of pilot flame, but not in the flame. Thermo couplers are inexpensive and easy to change out.

it sounds more like the ignitor thats messing up, if you are able to remove it and get a new one that would probobly do it for you