The first start of the day is the problem. After that (up to 6 hours later), it starts up just fine. Has 122,000 mi. Lexus says don't need to replace gas filter (haven't). Also have CEL for engine coolant temperature circuit. Have replaced sensor three times, and catalytic convertors (have not replaced O2 sensors). Rebuilt the ECM. Why can't I clear this code?

My lexus ls400 is hard to start when cold

The first start of the day is the problem. After that (up to 6 hours later), it starts up just fine. Has 122,000 mi. Lexus says don't need to replace gas filter (haven't). Also have CEL for engine coolant temperature circuit. Have replaced sensor three times, and catalytic convertors (have not replaced O2 sensors). Rebuilt the ECM. Why can't I clear this code?

Anonymous Sep 21, 2012

CEL code showing for the ECT sensor circuit is P0115
Anonymous Sep 25, 2012

No, the sensor replaced was the two-wire (larger) sensor, not the one-wire sender. They put it in without re-using the copper washer. There's supposed to be a third sensor (thermal time switch??), but I can't find it, and don't know if it can trigger code P0115..

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Stephen

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Posted on Sep 22, 2012

Stephen

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The code for the sensor is the giveaway.
The computer does not know how much fuel to give the injectors without that sensor working. The computer uses a factory set default reading.
Assuming the cooling system is full of fluid, you should be able to test the circuit and the sensor with a meter and a scanner. The sensor is a resistance variable that takes a 5 volt reference from the computer and changes it depending on the resistance in the sensor.
The sensor should read different resistance at different engine temps, and the harness should carry the voltage back to the computer. The scanner should show the sensor reading as the engine warms up.

Stephen Sep 22, 2012

BTW - is it possible you have replaced the sending unit for the temp gauge on the dash instead of the sensor for the computer ?

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Anonymous

776 Answers
Posted on Jun 28, 2009

SOURCE: 2005 HYUNDAI ACCENT ERROR CODE 0340 AFTER TIMING BELT REPLACEMENT

Here's what the shop manual says.

Anonymous

1 Answer
Posted on Jul 23, 2009

SOURCE: 1993 Lexus LS400 acceleration stalls or surges

I HAD THE SAME PROBLEM WITH MY CAR. 93 LS 400. THAT WOULD BE YOUR FUEL FILTER OR THE FUEL PUMP GOING BAD. TRY CHANGING THE FILTER FIRST. THE DEALER TRIED TO CHARGE ME $980 TO CHANGE FUEL PUMP.

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