Why do quotes for this code vary so wildly?

Because there is no middle ground in the repair. The solenoid is a cheap part reached from the top of the engine, so that fix is a few hundred dollars. The phaser sitting behind it requires the timing cover to come off, and that access is most of the labour in the job — which puts it an order of magnitude higher. There is very little that costs anything in between. Until the diagnosis has separated a blocked solenoid from a worn phaser or chain, any quote is really two quotes, and a shop that gives you both numbers is being straight with you rather than hedging.

Should I replace the timing chain at the same time as the phaser?

On most V engines, yes, and the reason is arithmetic rather than caution. Reaching the Bank 2 exhaust phaser means the timing cover comes off, which is where nearly all the labour goes. With the cover off, that bank's secondary chain, tensioner and guides are exposed and cost comparatively little to replace. Reusing a chain with unknown wear means that if it needs doing later, you pay the entire access cost a second time. Ask the shop to show you the chain and tensioner condition while it is open so the decision is based on what is actually in there.

Why can one bank's chain be worn when the other is fine?

Because they are separate chains. Very few V engines drive all four camshafts from a single chain. The usual arrangement is a primary chain from the crankshaft, then a short secondary chain per bank linking that bank's intake cam to its exhaust cam, each with its own tensioner and guides. Those are independent wear items, and oil supply, load and heat are not identical between the two heads. So Bank 2 having slack while Bank 1 is tight is entirely normal — which is also why a correlation fault confined to one bank means something on a V engine that it could not mean on an inline engine with one chain.

The code only sets in traffic, never on the highway. Does that tell you anything?

It does, and it points toward wear rather than a failed part. Hot idle and low-RPM light load are the conditions where oil pressure is lowest and chain slack is greatest, so a marginal phaser or a stretched secondary chain misbehaves there and copes fine at higher RPM where pressure is up and the chain is loaded. A component that has simply failed — a blocked solenoid, an open circuit — does not care what speed you are doing. If you are trying to reproduce the fault, sit at hot idle rather than revving it in the bay.

OBD-II trouble code

P0029: Exhaust Valve Control Solenoid Circuit Range/Performance (Bank 2)

The exhaust camshaft phaser on Bank 2 is not achieving its commanded position. What sets this code apart from the rest of the variable valve timing family is a cost question: on most V engines each bank has its own secondary chain and tensioner, and reaching this phaser opens the timing cover — so the quote is usually about the chain, not the solenoid.

Medium severityPowertrainVariable Valve TimingDrivable short-term

Quick facts

System: Powertrain
Category: Variable Valve Timing
Severity: Medium severity
Drivable: Usually safe to drive short-term
Repair cost range: $90 – $2,600
DIY difficulty: Advanced DIY

What does P0029 mean?

A range/performance fault on a valve timing solenoid means the electrical command went out, the circuit answered, and the camshaft still did not reach or hold the position the module asked for. The module knows because it watches cam sensor position against crank position continuously. This particular code names the exhaust camshaft on Bank 2 — the bank that does not contain cylinder one, which means the code only exists on V, flat and W engines.

The most useful thing to understand about this code is not electrical at all: it is how the camshafts on that bank are driven. Very few V engines run one chain to all four camshafts. The common arrangement is a primary chain from the crankshaft to an idler or to one cam on each head, and then a short secondary chain per bank connecting that bank's intake cam to its exhaust cam, each with its own tensioner and guides. That architecture has two consequences that matter here.

The first is diagnostic. A cam-to-crank correlation problem confined to Bank 2's exhaust cam raises a question an inline engine never poses, because on an inline engine there is one chain and a stretched chain affects everything at once. Here, Bank 2's secondary chain, its tensioner and its guides are a separate wear item from Bank 1's, and they can be worn while the other bank is fine. A worn secondary chain lets the exhaust cam sit slightly out of phase and lets it wander under load, which is precisely a range/performance signature: the phaser is working, but the reference it is working from has slack in it. When this code appears together with a Bank 2 cam correlation code, the chain moves ahead of the solenoid on the list of suspects.

The second is financial, and it is the reason this code is worth explaining carefully to an owner. An exhaust valve control solenoid is a cheap part that is usually accessible from the top of the engine. The phaser behind it is not: getting to it means removing the timing cover on that bank, and that is the great majority of the labour in the job. Once the cover is off, the chain, the tensioner and the guides are exposed and are a fraction of the remaining cost to replace. Fitting a phaser and reusing a chain with unknown wear on it means accepting the risk of paying that same access cost a second time. This is why quotes for this code cluster into two very different numbers — a solenoid, or a complete timing service — with little in between, and why the honest answer to what it costs depends on what the inspection through the cover finds rather than on the code itself.

Before any of that, the routine causes have to be cleared, and they are cheap. Oil level, oil age, and the correct viscosity account for a large share of these codes on their own. A solenoid with a debris-blocked screen is next. It makes no sense to plan timing work before an oil change and a solenoid inspection have been ruled out.

There is a timing detail in when the fault appears. Marginal phasers and worn chains both misbehave when oil pressure is at its lowest and slack is at its greatest, which is hot idle and low-RPM light load rather than wide-open throttle. A code that sets sitting in traffic and never on the motorway is consistent with wear rather than with a failed component, and it is worth testing under those conditions rather than by revving the engine in the bay.

Driveability effects are usually mild — a slightly uneven idle, a marginal loss of refinement, a small fuel economy penalty — and the emissions consequence is the same internal exhaust gas recirculation loss that any exhaust phaser fault produces, confined to one bank. Owners typically report nothing but the warning light.

Common causes

Low oil level or overdue oil, the cheapest and most common cause on any valve timing range/performance code
Wrong oil viscosity for the engine
Clogged screen on the Bank 2 exhaust valve control solenoid
Sticking solenoid spool that responds slowly rather than failing outright
Worn Bank 2 secondary chain, allowing the exhaust cam to sit out of phase and wander under load
Worn or collapsed Bank 2 chain tensioner, which is a separate wear item from Bank 1's
Worn chain guides on Bank 2 permitting slack the tensioner can no longer take up
Worn exhaust cam phaser on Bank 2 unable to hold its commanded position
Failed phaser lock pin producing a brief start-up rattle before oil pressure builds
Damaged wiring or a poor connection at the solenoid, degrading response without opening the circuit

Symptoms

Check engine light with P0029 stored and little or no driveability complaint
A Bank 2 camshaft position correlation code stored alongside this one
Code setting at hot idle or in stop-start traffic rather than under hard acceleration
Brief rattle from the timing cover on start-up
Slightly uneven idle and a small loss of refinement
Modest fuel economy penalty
Emissions readings higher than expected while the vehicle still drives normally
Bank 2 fuel trim marginally offset from Bank 1

Diagnostic steps

1.Check oil level, oil age and viscosity first, and correct any of the three before going further. This is the cheapest possible fix and it resolves a meaningful share of these codes.
2.Remove the Bank 2 exhaust valve control solenoid and inspect the screen for debris; confirm the spool moves and returns freely under light pressure.
3.Swap the exhaust solenoids between banks if the part numbers match, and see whether the code follows the part. That settles the solenoid question without buying anything.
4.Read companion codes carefully. A Bank 2 cam correlation code stored with this one shifts suspicion onto that bank's secondary chain and tensioner rather than onto the solenoid.
5.Test at hot idle and low-RPM light load, not by revving in the bay. Slack and low oil pressure are both worst under those conditions, which is where wear reveals itself.
6.Graph commanded against actual Bank 2 exhaust cam position, watching how quickly it responds and whether it holds once it arrives.
7.Measure oil pressure at operating temperature with a mechanical gauge if both banks show sluggish response, since an engine-wide supply shortfall can present on one bank.
8.Inspect Bank 2 chain and tensioner condition before committing to a phaser. On most V engines this bank has its own secondary chain, which can be worn while the other bank is healthy.
9.If the timing cover is coming off, inspect and cost the chain, tensioner and guides at the same time. The access labour is already spent, and reusing a worn chain risks paying it again.

Repair cost

$90 – $2,600

The two realistic outcomes on this code are far apart. An oil change with the correct grade is $90 to $180 and a Bank 2 exhaust valve control solenoid is roughly $140 to $400 fitted, both of which are top-of-engine work. If the phaser or that bank's secondary chain is at fault, the timing cover has to come off and the labour dominates — commonly $1,400 to $2,600 for a phaser and chain service on a V engine, with the parts themselves a modest share of that. Because the access cost is the same either way, replacing the chain, tensioner and guides while the cover is off is usually the sound decision rather than an upsell. Get the cheap causes cleared first so that quote is only needed if it is genuinely warranted.

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DIY vs shop

This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.