Bosch C 1210 ESC Reference manual

Technical Service Bulletin:

A2 Error Code Troubleshooting

Models: C1210ESC, C1210ES, C1050ES, C950ES, 940ES, 940ESO, 830ES, 2400ES,

2700ES, 715ES, C800ES, C920ES/ESC, Integra 500, Evolution 500

Introduction

This procedure must be performed by a qualiﬁed technician.

Follow the procedures below and report results to Bosch Technical

Support. This will assist in determining the cause and solution to the

problem.

A2 error code

This error code detected by the ﬂue gas limiter indicates a possible

exhaust leak from the combustion chamber.

Flue Gas Limiter

The ﬂue gas limiter is a safety device located in the upper right

corner of the heater that is designed to trip (creating an open

circuit) if the chamber outside the heat exchanger exceeds 220 °F or

104 °C.

The limiter will reset itself (closing the circuit) when it cools off, but

the error will still have to be reset manually using the reset button

on the control board.

Tools needed:

Phillips head screwdriver

Digital Multi-meter

Procedure

1. Press the “reset” button on the control panel of the

heater to clear the error code. If the error code does not

reset or continues to reoccur, proceed with the following

troubleshooting steps.

2. Conﬁrm that the heater is installed according to the

speciﬁcations in the manual.

Confirm that the exhaust and intake pipes are the correct

diameter, material and approved length as explained in the

installation manual provided with your model.

3. Remove cover per the installation manual and verify that the

plug connector between the ﬂue gas limiter (white wires) and

the control unit (black wires) is ﬁrmly connected (see Fig. 1).

Figure 1

The ﬂue gas limiter (see Fig. 2 A) should not be confused

with the overheat sensor (ECO) on the upper right corner

of the heat exchanger (see Fig. 2 B). The ECO serves an

entirely different function and prompts a different – E9 –

error code.

Figure 2

Data subject to change without notice | Printed in the USA | BTC 740002331 A | 05.2014 Bosch Thermotechnology Corp.

Technical Service Bulletin

2 | A2 Error Code Troubleshooting

Bosch Thermotechnology Corp.

50 Wentworth Avenue

Londonderry, NH 03053

Tel: 1-800-283-3787

Fax: 1-603-965-7581

www.bosch-climate.us

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 ﬂue 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 ﬂue 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 call us while still at

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 [email protected]h.com and we will reply

within one business day.

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