Tons Of Trouble Codes

[aread4]

I took my 1999 RX 300 (62,000 miles) to the dealer about 2 weeks ago to install a new alternator and Mass Air Flow Sensor (they recommended the sensor since my CEL was on). Ever since, my mpg have gone from 20 to 8!! And now I've got P0300, P0301, P0303, P0305, P0171, P1130, P1133, and P1135!!

A/F Ratio sensors (O2 sensor bank 1, sensor 1) is getting replaced tomorrow, along with my cracked front exhaust manifold. But I worry about the 1st 4 codes since they are cylinder misfires. After reading earlier threads I'm also thinking I may need to change out my knock sensor since it won't shift to overdrive, but keeps climbing up to 4200 rpm at 60mph.

Have I set a new record for the most # of codes at one time? Does anyone think the dealer may have screwed something up? Please help I've got some major issues here. Thanks in advance.

[RX in NC]

From your description, there's certainly a chance that your dealer did not properly reinstall your hoses and connections after replacing your alternator and mass air flow sensor a couple of weeks ago. The fact that your gas mileage dropped from 20 mpg down to 8 mpg immediately after your vehicle was serviced points to that conclusion. Have you discussed this problem with them? If so, what was their response? Technicians in a hurry or not completely familiar with the procedure they're performing often make mistakes such as failing to restore all connections properly, and this could be the source of SOME of your current problems.

But you also need to be aware of the fact that a cracked exhaust manifold is a very common problem in 1999, 2000, and 2001 RX300s. When a manifold cracks in these vehicles, it can cause the ECU to throw a variety of codes which may or may not be accurate. I know this because my wife's 2000 RX300 experienced a cracked exhaust manifold at about 45,000 miles and threw a number of codes as a result. But the only code that turned out to be accurate after the manifold was replaced was the mass air flow sensor. Fortunately for us, all of these problems were covered under warranty at that time.

My advice to you is two-fold: First, have your cracked exhaust manifold replaced (and all of your hose and electrical connections visually checked out) and then have the codes read again before they do any additional work to your vehicle because you may find that many of those codes have magically disappeared once the new manifold is in place. Second, approach the dealership's service manager with the knowledge you've gained about the very common cracked exhaust manifold problem and ask them to cover it for you under their "goodwill" warranty policy. I've had our local Lexus dealership cover various failures on my wife's vehicle under this little-known "goodwill" policy even as her vehicle was approaching 75,000 miles. It never hurts to ask. Just be professional, but firm, when you approach them about it, and make them aware that you've done significant research on exhaust manifold cracking on the RX300 series and you now know that it is a common failure in these vehicles.

Good luck to you and keep us posted on your situation....

[aread4]

Excellent reply. I'll do just that after I get the manifold replaced today. Thanks for the timely response. I'll let you know what transpires. Thanks again!

From your description, there's certainly a chance that your dealer did not properly reinstall your hoses and connections after replacing your alternator and mass air flow sensor a couple of weeks ago. The fact that your gas mileage dropped from 20 mpg down to 8 mpg immediately after your vehicle was serviced points to that conclusion. Have you discussed this problem with them? If so, what was their response? Technicians in a hurry or not completely familiar with the procedure they're performing often make mistakes such as failing to restore all connections properly, and this could be the source of SOME of your current problems.

But you also need to be aware of the fact that a cracked exhaust manifold is a very common problem in 1999, 2000, and 2001 RX300s. When a manifold cracks in these vehicles, it can cause the ECU to throw a variety of codes which may or may not be accurate. I know this because my wife's 2000 RX300 experienced a cracked exhaust manifold at about 45,000 miles and threw a number of codes as a result. But the only code that turned out to be accurate after the manifold was replaced was the mass air flow sensor. Fortunately for us, all of these problems were covered under warranty at that time.

My advice to you is two-fold: First, have your cracked exhaust manifold replaced (and all of your hose and electrical connections visually checked out) and then have the codes read again before they do any additional work to your vehicle because you may find that many of those codes have magically disappeared once the new manifold is in place. Second, approach the dealership's service manager with the knowledge you've gained about the very common cracked exhaust manifold problem and ask them to cover it for you under their "goodwill" warranty policy. I've had our local Lexus dealership cover various failures on my wife's vehicle under this little-known "goodwill" policy even as her vehicle was approaching 75,000 miles. It never hurts to ask. Just be professional, but firm, when you approach them about it, and make them aware that you've done significant research on exhaust manifold cracking on the RX300 series and you now know that it is a common failure in these vehicles.

Good luck to you and keep us posted on your situation....

[anthonyiez]

working from memory here so forgive me a bit...

1st... i agree with the above chances are they screwed something up, but its the dealer and they're the best and never screw up...LOL

2nd...in 1999 toyota had a problem with cali emission 3.0 v6 engines concerning the fuel injectors. they have updated injectors.

my guess is they screwed something up, but just wanted to throw that other info out there.