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P0026, P0027 Error Codes - Updated!

3187 Views 2 Replies 1 Participant Last post by  Skiahh, 
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Newbie here....read all I could find on this error code. I have a 2.5, non-turbo. Last year had an error code P0027. Chased this out to the Exhaust VVT solenoid valve which I purchased at NAPA. While in there, I also replaced the pressure switch, both were on the left side of the engine toward the front. Solved the problem. Error code P0027 cleared. Now a year later have a P0026 error code. First attempt was to replace the Intake VVT solenoid valve located on the right side of the engine, toward the rear of the bank. This however did not clear the error code. I used the OBD II to reset the codes, but the same P0026 came right back on after restarting the engine with the new valve. The new part came from Advanced Auto. Rechecked installation of the new valve and wiring....all are correct, its a simply job to swap out this VVT.

I realize P0026 is not just the solenoid valve, but also the entire circuit. My questions are related to testing the circuit. I'm under the impression the wire from the intake solenoid (2-wire lead) probably goes to the ECM. If I unplug from the solenoid, what tests can I run? I can check continuity to ground on both leads, what should I be seeing or not seeing? If I measure resistance across the new VVT solenoid, what should I see for resistance (I'm assuming my new VVT is good, but what if it is bad out of the gate)? I still have the old VVT and can check continuity on that as well. Any other suggestions for checking the circuit would be appreciated. A wiring diagram would be great if I could find one so I could figure out the routing in case there is a short somewhere. General information on the routing of the wiring from the Intake VVT might help me.

I see plenty of suggestions for oil change and possible flushing with Marvel Mystery Oil or Seafoam (partial mixture of these products with oil, run for a short time/distance followed by another oil change...idea is to remove any sludge. The car has 105,000 miles...it has had the common head oil leak serviced by a reputable shop, all top end recommended modifications/repairs were completed (timing belt, etc.). Car has regular oil/filter changes (3,000 to 5,000 miles) and I use full synthetic in the recommended viscosity range. Do you think it may be worth my while to attempt a flush in this manner?
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P2006 Error Code

OK, no responders yet, but I did some more research. In order to test the wiring harness I'll need to disconnect the lead at both ends, one at the VVT, other at the ECM. Once done, I can then run a test to determine if the harness is shorted.

Been looking for wiring diagrams on-line, but no luck so far. Does anyone out there know which plug I'd need to disconnect from the ECM to disconnect the intake VVT?

Aside from that, oil level needs to be checked....done and OK. Since I just replaced the valve, unless it is faulty out of the box, I should be OK there....I will run a continuity test on the new VVT just to be sure.

Beyond that I could also have a problem with the ECM. This would require more instrumentation than I have at home and I'll probably need to bring it to a shop for proper testing.
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Still no responders, but the problem is now solved, perhaps this will help someone else. As stated above, the P0026 is not just the variable valve, but the entire circuit which includes the variable valve. Using a voltmeter, I checked the resistance and it seems there was nothing wrong with the original variable valve or the new one. I was trying to learn where the leads go from this valve back to the ECM (electronic control module). From what I could see it is a simply connector containing only two wires.

Took a while, but found that the connection at the right variable valve is referred to #71. This goes to another connector identified as B22 terminal 21 which goes then goes to the ECM terminating at B134, terminal 31. My next move was going to be testing the wiring in this circuit for any shorts or grounding, but I did not get that far.

In the meantime, we noticed oil leaking from a pressure sensor directly adjacent to the right variable valve (just forward). I never bothered to look up the function of this sensor, but figured we needed to replace it because it was leaking. As far as I know, this sensor is not part of the P0026 circuit, however, it does look like it is screwed into the same oil passage as the variable valve. We replaced this sensor, cleared the P0026 error code and it appears to have fixed the problem. The P0026 error code has now been gone for over a month with no reoccurrence. This has me wondering if the oil leak at this sensor was causing a slight pressure drop in the oil passage causing the valve timing to be off, hence generating the error code?

I've attempted to upload the files I found with respect to the wiring of the right variable valve circuit. I'm not a certified mechanic, have not traced these wires to confirm this information is correct.

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