Mystery Loosing Coolant and P0171 Code return (Gen4, 5SFE) - Toyota Nation Forum : Toyota Car and Truck Forums

Ichiban Rhino · 06-09-2011, 08:28 AM

Couple weeks age I've noticed the coolant reservoir tank got down to Low mark. So I added and up to Full mark. This morning the CEL comes on, I popped the hood to see what's going on, and notice the coolant level is on Low mark again. Looked around did not see any sign of coolant leak. Ran test on CEL code is P0171 system too lean. Questions:
1. What cause the coolant loosing? Head Gasket blown?
2. The code P0171 was off and on for the last 4 months (I put K&N air filter, cleaned TB, replaced Intake Air hose 5 months ago, switched to Synthentic Oil last week). Is any of these thing cause the code come back?

Is there anything i need to do/ check before head to the shop for coolant check?
thanks in advance.

98 Camry 115000 Miles. Water pump replaced at 85,000 miles.

csharp100 · 06-09-2011, 08:58 AM

A few things will need to be looked at. Were there any pending codes when you read the codes off the reader? Pending codes are codes that are "ready" to come up but the ECM has deamed them not a priority. Check the color of your oil? Is it milky? Do a compression test. This will tell you what is going on internally. Running lean could mean a vacuum leak and the head gasket could be to blame.
This needs to be checked pretty quickly. Coolant getting into the combustion chanber is not a good thing. Once coolant gets past the combustion chamber and into the exhaust, coolant and catalyst do not mix. Catalyst can be destroyed by cooland and then you are stuck with not only replacing the head gasket but they catalytic converter as well.

***Mister_Perkins*** · 06-09-2011, 08:40 PM

First, go to Autozone or advanced auto and rent a Radiator Pressure check tool. Pressurize the system, and look with a light around for leaking coolant. If no coolant is found, do a compression check, Leak-down check, and Hydro carbon test.

Ichiban Rhino · 02-08-2012, 04:51 PM

After replacing ThermalStat the leak seems to stop until last week. I open the hood to replace air filter, and notice the coolant in reservoir tanks was nearly at Low. So there i was jacked it up and craw down... and found the leak came from the connector of trans fluid cooler line to radiator. Here's my questions.
Should i go to dealer for connector or local store? what brand?
Do i have to drain the coolant and trans fluid to replace it?