Bosch C1210ESC Technical Service Bulletin page 2

2 | A2 Error Code Troubleshooting
4. Inspect the heat exchanger for signs of exhaust leakage:
Perform a visual inspection of the heat exchanger, looking

for any signs of cracks or burn marks.
Visually inspect the gaskets on the top and bottom of the

heat exchanger to ensure the gaskets are properly seated.
Inspect the gaskets for any burned or melted sections.

Inspect the viewing window on the heat exchanger for any

cracks in the glass or breaks around the window gasket.
Inspect the gasket around the electrodes. Ensure holding

clamps are tight and secure.
 If the heater can be reset and operated, pass a telescoping
mirror at and around all gaskets with the heater running. A
fogging mirror is a sign of a leak.
DANGER:
Any damaged gaskets allowing fl ue gasses to leak
must be replaced. Failure to replace the gaskets and
continued operation can lead to serious illness or even
death.
5. Inspect the exhaust and intake terminations for any
obstructions and clear if needed.
6. Check the resistance on the fl ue gas limiter as outlined below:
 Set your digital multi-meter to ohms if an auto ranging
meter or 200 ohms if you need to set the range.
locate the flue gas limiter in the upper right hand corner of

the machine.
Insert one probe into each wire at plug connection.

Resistance should be 0.5 ohms or less. If there is no
continuity or the resistance is too high, the flue gas limiter
needs to be replaced.
After completing this procedure, please
the unit at 1-800-798-8161 for diagnosis and resolution. If
it is more convenient for you, please email the results of
this procedure to ldy.asa@us.bosch.com and we will reply
within one business day.
Data subject to change without notice | Printed in the USA | BTC 740002331 A | 05.2014
call us while still at
Technical Service Bulletin
Bosch Thermotechnology Corp.
50 Wentworth Avenue
Londonderry, NH 03053
Tel: 1-800-283-3787
Fax: 1-603-965-7581
www.bosch-climate.us
Bosch Thermotechnology Corp.