P0021 Code w/ Check Engine Light (1 Viewer)

[fjrohrs]

Afternoon Mud,

I've done some generic googling as well as searched here on mud for possible reasons why I'd be throwing the P0021 code on my 2006 TLC.

This is what I've found so far:
A code P0021 refers to the VVT (variable valve timing) or VCT (variable camshaft timing) components and the car's PCM (powertrain control module, also called an ECM). That consists of a few different components but the P0021 DTC specifically refers to the camshaft (cam) timing. In this case, if the cam timing is above a set limit (over-advanced), the engine light will be illluminated and the code will be set. The "A" camshaft is either the intake, left, or front camshaft. A P0021 engine code is basically the same as a P0011 code, except this is for Bank 2, not Bank 1.
Potential Symptoms

Most likely a P0021 DTC will result in one of the following: hard starting, poor idle, and/or stalling. There are potentially other symptoms as well. Of course, when trouble codes are set, the MIL (malfunction indicator lamp, a.k.a. the check engine light) illuminates.
Causes

A P0021 DTC trouble code may be caused by one or more of the following:
Incorrect camshaft timing
Wiring problems (harness/wiring) in intake timing control valve control solenoid system
Continuous oil flow to VCT piston chamber
Failed timing valve control solenoid (stuck open)
B]Possible Solutions[/B]

This DTC code is a result of a mechanical fault of the VCT unit or related components, so there is no need for electrical diagnosis. Refer to vehicle specific repair manual to perform component tests for the VCT unit. Notes: Dealer techs have advanced tools and the ability to follow detailed troubleshooting steps, including the ability to test components using a scan tool.


So, the pertinent information:
2006
96,100 miles
Timing belt has not been done - it's on the list but will possibly be expedited now

Truck runs fine with no noticeable rough idle, loss of power, etc. Mileage has been a little down lately ~11mpg in town versus ~12.5 previous. Thanks and I look forward to your thoughts.



Would my problem be fixed if I do the timing belt or would I need to replace/fix anything else?

 

[marshotel]

Occam's razor says: clear the code, then disconnect the the battery overnight.

When you reconnect the battery, let it idle for about an hour and see if you get the dash light.

If you keep getting the light, then i guess you should check or change your camshaft position sensors at the same time you do the timing belt. I have heard that the camshaft position sensors are located under the timing belt cover and they cost about $100; sometimes they get stuck and need lubrication or replacement. Should be easy to fix if you are already in there for the TB.

I have never heard of problems with the actual VVT system, and suspect your code is the result of a stuck cam position sensor. Others will know more about it...

Hope this helps.

 

[fjrohrs]

Occam's razor says: clear the code, then disconnect the the battery overnight.

When you reconnect the battery, let it idle for about an hour and see if you get the dash light.

If you keep getting the light, then i guess you should check or change your camshaft position sensors at the same time you do the timing belt. I have heard that the camshaft position sensors are located under the timing belt cover and they cost about $100; sometimes they get stuck and need lubrication or replacement. Should be easy to fix if you are already in there for the TB.

I have never heard of problems with the actual VVT system, and suspect your code is the result of a stuck cam position sensor. Others will know more about it...

Hope this helps.

That's great information! I will disconnect the battery this evening and then see how it does. Will I do any damage driving it in the meantime? I cleared the code with my scangauge 2 and am waiting for it to come back but will also disconnect.

 

[fjrohrs]

One last thing: is the only way to know if the sensor is bad/stuck if the code returns? IE. if the code doesn't come back for a while, I replace the TB, but then it returns at a later date.

 

[marshotel]

I don't think you'll do any damage driving it in the mean time, but others will know more...

If the code comes back, I would just change out the sensor responsible for the code at the same time you do the timing belt. Considering the check engine light, I would probably move that job to the top of the list.

Of course, it is possible that there is an actual problem with the timing (VVT system), but that would be pretty unusual.

Disclaimer: I've never actually wrenched on a VVT 2UZ-FE so this information is worth exactly what you're paying for it. I hope some of the more experienced guys will chime in here....

 

[fjrohrs]

I don't think you'll do any damage driving it in the mean time, but others will know more...

If the code comes back, I would just change out the sensor responsible for the code at the same time you do the timing belt. Considering the check engine light, I would probably move that job to the top of the list.

Of course, it is possible that there is an actual problem with the timing (VVT system), but that would be pretty unusual.

Disclaimer: I've never actually wrenched on a VVT 2UZ-FE so this information is worth exactly what you're paying for it. I hope some of the more experienced guys will chime in here....

Information is appreciated none-the-less. Thanks for replying!

 

[jon91581]

Hey guys,

Sorry for reviving an old thread, but I figured it'd be better to add to an existing thread about a similar problem that I'm encountering with a 'P0021' fault code. I've had the code read at a local repair shop, and they said that the sensor is functioning properly.

If I reset the ECU by disconnecting the battery, the engine light goes off, as well as the VSC and TRAC lights. I haven't pinpointed the situation for exactly when they come back on, but it's usually after driving for a few days.

Car drives fine, no rough idle, throttle surging, noticeable power loss or any other symptoms. Timing belt was most recently changed just over three years and 27,000 miles ago.

Any thoughts or recommendations to help trouble shoot resolve the issue?

Thanks,
Jon

 

[jon91581]

Just curious if anyone had any ideas about what could be causing a P0021 fault code intermittently even though the camshaft position sensor seems to be functioning properly. Perhaps a bad ground?

The light most recently came on after the truck had been sitting for a couple of days and the temperature/weather changed quite a bit. Only symptom was a brief idle stutter at start up and then the light came on (plus VSC and TRAC lights).

Thanks,
Jon