Weird P1121 after valve replaced

Bought a 2004 Gen2 210,000 km two weeks ago. The seller said there used to be ECL as the known issue, but everything was ok after he had the coolant valve replaced 2 days before. Driven for about 600km since then.

The light comes on today, OBD II says P1121. Cleared, comes on again.

Checked the coolant, both inverter and engine reservoir seem to have above the min level coolant. Car blows warm air with no problem.

Need inputs on the possible root cause or likelihood on these below from my research so far:

1. Mechanic didn't do it right. a)problematic (used) part installed, b)coolant wasn't drained/refilled correctly, air in cooling system, could this cause ECL after driving 600km?

2. Loose/rotten electric connector

3. Coolant leakage (I didn't find any but will check again)

4. Bad ECM

5. Seller lied

 

Checked coolant, full under radiation cap and in both reservoirs.

Cleared the code, tested 2 miles, nothing happened.

 

Thanks for helping.

The bracket look okay, valve has some white removable spots on it (I put both before and after pics), not sure if it's brand new. I'll call the shop next week to find out.

Good news is a rag on the bottom cover under the valve. At least someone has done something about the cooling system.

Didn't find a way to access the CHS sensor. Will check the manual later.

Still trying to understand when the value should move. That is probably when I should expect the next check engine light.

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Tried resetting the light a couple of times. It's quite obvious the light comes on every time I start the car, no matter overnight or after a long trip.

 

Called the shop the seller had the valve replaced. The owner said they only use new parts. From the picture above I believe it's true. Then it's quite unlikely for a new valve to fail in 2 weeks/1000km.

Will check CHS sensor and wiring, but one question: Shouldn't I have got P1116 and P1150 if the sensor/wiring failed?

 

Where the clogging might happen, inside the hoses/radiator or among the fins of the radiator?

 

Thank you John. I'll definitely give a try.

When did you have the code, right after the change or a while later? Mine start throwing the code after about 600km. Checked coolant is full. If the engine runs with air in the system, should I be more concerned of overheating/damage than the code itself?

 

Ran the pump from CHS relay with multimeter and half funnel of coolant on radiator. 20 sec 3 times. The current reads 3.07A, but not a single bubble shows up in the funnel.

Does it mean a lot of air in the cooling system? Why didn't it bleed?

 

[Status]

Radiator and reservoir full of coolant. Road test with max heat and low fan speed, very hot air blown. Reservoir coolant level does not drop after 5miles test drive. Engine temp normal 176F max with ambient 37F. ECL P1121 cleared but comes back almost every time car is started. Water sloshing sound after switch off. Bought clear vinyl tube for bleeding air from radiator. Ordered Mini VCI.

[Likely Causes]

1. Replaced valve goes wrong again (it could be aftermarket part)
2. Valve stuck by debris in coolant (the previous owner may not have changed coolant)
3. CHS sensor wiring

[Action Plan]

• Call the shop again to confirm aftermarket or OEM part
• Check sensor wiring
• Try bleeding air from CHS relay socket with radiator bleed valve open.
• Plan to change coolant in near future

 

Tried CHS relay again with radiator cap off and radiator bleed valve open (6mm hex), 20 sec x 3 times, nothing happens at all.

Coolant pump draws about 3.2A current which is lower than 4A normal value suggested in most Youtube channels. Does it suggest air in the coolant passages?

 

After cleared a couple P1121 in the last few days, it throws P1122 today. Does it suggest high likelihood of valve failure?

 

Called the shop again. The owner said he "don't remember" where he got the valve.

Anyway, I'll just try a new OEM valve and change the coolant as safety measure to a used car.

 

Update: problem solved by changing the control valve to genuine part.

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