Code 89 keeps reappearing

Hi,

The code, 89, isn't listed in the manuals, but I have heard others speak of it related to the thermostat. When the thermostat was replaced, did they also replace the thermostat housing? This thermostat is electronically controlled, and from what I gather, the electronics in the housing go bad.

Take a look at the attached pic. I circled the thermostat in red and the housing in blue. Were both components replaced?

Let me know if you have had the computer scanned with a scan tool. If so, let me know what P code was found.

Let me know.
Joe

Yes, both components were replaced. A computer scan was done, but no problem codes were detected.

Hi, Ada. Since you only have the 89 code, at this point, I would check the electrical components related to the electronic thermostat items. I am going to provide the directions, but it does require a scan tool that can actuate different components.

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DIAGNOSIS:

See pic 1

1. Disconnect the harness connector at the E41 Engine Coolant Thermostat Heater. Ignition ON, verify a test lamp illuminates between the ignition circuit terminal 2 and ground.
- If the test lamp does not illuminate, repair the open or shorted circuit and retest.
- If the test lamp does illuminate, proceed to the next step.

2. Using a capable scan tool command the E41 Engine Coolant Thermostat Heater to 100%. The voltage should transition from 2.5–3.5 volts when commanded to 10% to less than 0.1 volt when commanded to 100%.
- If the circuit voltage does NOT correspond to the specified values and the circuit is ok, replace the K20 Engine Control Module.
- If the circuit voltage does correspond to the specified values, replace the E41 Engine Coolant Thermostat Heater.

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I wish I had an easy answer, but replacing the components indicates a different issue. That is where the diagnostics need to come into play.

Let me know if I can help in any way or if you have other questions.

Take care,
Joe

Ada,

I have a question. When the coolant was replaced in your vehicle, was the correct type used? The vehicle would have come with DexCool coolant. It can't be mixed with standard types of coolant. Also, do you have the receipt for the parts and can you provide the part numbers? The wrong part can appear the same and be different.

Let me know. I'm trying to narrow this down.

Joe